_.orderBy(collection, [iteratees=[_.identity]], [orders])
82
_.orderBy(collection, [iteratees=[_.identity]], [orders])
_.orderBy和sortBy类似，允许指定遍历器遍历的时候排序次序的条件。如果没有指定排序的条件，默认升序。另外，可以指定order参数为desc作为降序，asc作为升序。也可以指定一个比较方法作为排序的条件
参数
collection (Array|Object): 需要遍历的集合
[iteratees=[_.identity]] (Array[]|Function[]|Object[]|string[]): iteratees遍历生成排序时比较的标准，通过比较标准来决定结果的顺序
[orders] (string[]): 比较使用升序或者降序，或者自定义比较方法
返回值
(Array): 返回排好顺序的新数组
例子
var users = [ { 'user': 'fred', 'age': 48 }, { 'user': 'barney', 'age': 34 }, { 'user': 'fred', 'age': 40 }, { 'user': 'barney', 'age': 36 } ]; // Sort by `user` in ascending order and by `age` in descending order. _.orderBy(users, ['user', 'age'], ['asc', 'desc']); // => objects for [['barney', 36], ['barney', 34], ['fred', 48], ['fred', 40]]
源代码：
省略iteratee的处理，想看iteratee的处理看这里，https://www.cnblogs.com/hahazexia/p/9901435.html
/** * lodash (Custom Build) <https://lodash.com/> * Build: `lodash modularize exports="npm" -o ./` * Copyright jQuery Foundation and other contributors <https://jquery.org/> * Released under MIT license <https://lodash.com/license> * Based on Underscore.js 1.8.3 <http://underscorejs.org/LICENSE> * Copyright Jeremy Ashkenas, DocumentCloud and Investigative Reporters & Editors */ /** Used as the size to enable large array optimizations. */ var LARGE_ARRAY_SIZE = 200; /** Used as the `TypeError` message for "Functions" methods. */ var FUNC_ERROR_TEXT = 'Expected a function'; /** Used to stand-in for `undefined` hash values. */ var HASH_UNDEFINED = '__lodash_hash_undefined__'; /** Used to compose bitmasks for comparison styles. */ var UNORDERED_COMPARE_FLAG = 1, PARTIAL_COMPARE_FLAG = 2; /** Used as references for various `Number` constants. */ var INFINITY = 1 / 0, MAX_SAFE_INTEGER = 9007199254740991; /** `Object#toString` result references. */ var argsTag = '[object Arguments]', arrayTag = '[object Array]', boolTag = '[object Boolean]', dateTag = '[object Date]', errorTag = '[object Error]', funcTag = '[object Function]', genTag = '[object GeneratorFunction]', mapTag = '[object Map]', numberTag = '[object Number]', objectTag = '[object Object]', promiseTag = '[object Promise]', regexpTag = '[object RegExp]', setTag = '[object Set]', stringTag = '[object String]', symbolTag = '[object Symbol]', weakMapTag = '[object WeakMap]'; var arrayBufferTag = '[object ArrayBuffer]', dataViewTag = '[object DataView]', float32Tag = '[object Float32Array]', float64Tag = '[object Float64Array]', int8Tag = '[object Int8Array]', int16Tag = '[object Int16Array]', int32Tag = '[object Int32Array]', uint8Tag = '[object Uint8Array]', uint8ClampedTag = '[object Uint8ClampedArray]', uint16Tag = '[object Uint16Array]', uint32Tag = '[object Uint32Array]'; /** Used to match property names within property paths. */ var reIsDeepProp = /\.|\[(?:[^[\]]*|(["'])(?:(?!\1)[^\\]|\\.)*?\1)\]/, reIsPlainProp = /^\w*$/, reLeadingDot = /^\./, rePropName = /[^.[\]]+|\[(?:(-?\d+(?:\.\d+)?)|(["'])((?:(?!\2)[^\\]|\\.)*?)\2)\]|(?=(?:\.|\[\])(?:\.|\[\]|$))/g; /** * Used to match `RegExp` * [syntax characters](http://ecma-international.org/ecma-262/7.0/#sec-patterns). */ var reRegExpChar = /[\\^$.*+?()[\]{}|]/g; /** Used to match backslashes in property paths. */ var reEscapeChar = /\\(\\)?/g; /** Used to detect host constructors (Safari). */ var reIsHostCtor = /^\[object .+?Constructor\]$/; /** Used to detect unsigned integer values. */ var reIsUint = /^(?:0|[1-9]\d*)$/; /** Used to identify `toStringTag` values of typed arrays. */ var typedArrayTags = {}; typedArrayTags[float32Tag] = typedArrayTags[float64Tag] = typedArrayTags[int8Tag] = typedArrayTags[int16Tag] = typedArrayTags[int32Tag] = typedArrayTags[uint8Tag] = typedArrayTags[uint8ClampedTag] = typedArrayTags[uint16Tag] = typedArrayTags[uint32Tag] = true; typedArrayTags[argsTag] = typedArrayTags[arrayTag] = typedArrayTags[arrayBufferTag] = typedArrayTags[boolTag] = typedArrayTags[dataViewTag] = typedArrayTags[dateTag] = typedArrayTags[errorTag] = typedArrayTags[funcTag] = typedArrayTags[mapTag] = typedArrayTags[numberTag] = typedArrayTags[objectTag] = typedArrayTags[regexpTag] = typedArrayTags[setTag] = typedArrayTags[stringTag] = typedArrayTags[weakMapTag] = false; /** Detect free variable `global` from Node.js. */ var freeGlobal = typeof global == 'object' && global && global.Object === Object && global; /** Detect free variable `self`. */ var freeSelf = typeof self == 'object' && self && self.Object === Object && self; /** Used as a reference to the global object. */ var root = freeGlobal || freeSelf || Function('return this')(); /** Detect free variable `exports`. */ var freeExports = typeof exports == 'object' && exports && !exports.nodeType && exports; /** Detect free variable `module`. */ var freeModule = freeExports && typeof module == 'object' && module && !module.nodeType && module; /** Detect the popular CommonJS extension `module.exports`. */ var moduleExports = freeModule && freeModule.exports === freeExports; /** Detect free variable `process` from Node.js. */ var freeProcess = moduleExports && freeGlobal.process; /** Used to access faster Node.js helpers. */ var nodeUtil = (function() { try { return freeProcess && freeProcess.binding('util'); } catch (e) {} }()); /* Node.js helper references. */ var nodeIsTypedArray = nodeUtil && nodeUtil.isTypedArray; /** * A specialized version of `_.map` for arrays without support for iteratee * shorthands. * * @private * @param {Array} [array] The array to iterate over. * @param {Function} iteratee The function invoked per iteration. * @returns {Array} Returns the new mapped array. */ //类似_.map方法，只支持数组的遍历 function arrayMap(array, iteratee) { var index = -1,//循环索引 length = array ? array.length : 0,//数组长度 result = Array(length);//结果数组，长度和原数组一样 while (++index < length) {//循环调用iteratee处理当前元素然后插入结果数组 result[index] = iteratee(array[index], index, array); } return result; } /** * A specialized version of `_.some` for arrays without support for iteratee * shorthands. * * @private * @param {Array} [array] The array to iterate over. * @param {Function} predicate The function invoked per iteration. * @returns {boolean} Returns `true` if any element passes the predicate check, * else `false`. */ function arraySome(array, predicate) { var index = -1, length = array ? array.length : 0; while (++index < length) { if (predicate(array[index], index, array)) { return true; } } return false; } /** * The base implementation of `_.property` without support for deep paths. * * @private * @param {string} key The key of the property to get. * @returns {Function} Returns the new accessor function. */ function baseProperty(key) { return function(object) { return object == null ? undefined : object[key]; }; } /** * The base implementation of `_.sortBy` which uses `comparer` to define the * sort order of `array` and replaces criteria objects with their corresponding * values. * * @private * @param {Array} array The array to sort. * @param {Function} comparer The function to define sort order. * @returns {Array} Returns `array`. */ //sortBy的基础实现，使用比较方法决定最终数组元素的顺序，将criteria对象替换为其对应的原始值 function baseSortBy(array, comparer) { var length = array.length;//数组长度 array.sort(comparer);//调用原生sort排序 while (length--) {//将排好序的array中的元素替换为原始值 array[length] = array[length].value; } return array; } /** * The base implementation of `_.times` without support for iteratee shorthands * or max array length checks. * * @private * @param {number} n The number of times to invoke `iteratee`. * @param {Function} iteratee The function invoked per iteration. * @returns {Array} Returns the array of results. */ //times的基础实现 function baseTimes(n, iteratee) { var index = -1,//循环索引 result = Array(n);//结果数组长度 while (++index < n) {//结果数组每个元素是调用iteratee处理索引值的结果 result[index] = iteratee(index); } return result; } /** * The base implementation of `_.unary` without support for storing metadata. * * @private * @param {Function} func The function to cap arguments for. * @returns {Function} Returns the new capped function. */ //_.unary的基础实现，创建一个函数只接受一个参数，忽略之后所有参数 function baseUnary(func) { return function(value) { return func(value); }; } /** * Gets the value at `key` of `object`. * * @private * @param {Object} [object] The object to query. * @param {string} key The key of the property to get. * @returns {*} Returns the property value. */ function getValue(object, key) { return object == null ? undefined : object[key]; } /** * Checks if `value` is a host object in IE < 9. * * @private * @param {*} value The value to check. * @returns {boolean} Returns `true` if `value` is a host object, else `false`. */ function isHostObject(value) { // Many host objects are `Object` objects that can coerce to strings // despite having improperly defined `toString` methods. var result = false; if (value != null && typeof value.toString != 'function') { try { result = !!(value + ''); } catch (e) {} } return result; } /** * Converts `map` to its key-value pairs. * * @private * @param {Object} map The map to convert. * @returns {Array} Returns the key-value pairs. */ function mapToArray(map) { var index = -1, result = Array(map.size); map.forEach(function(value, key) { result[++index] = [key, value]; }); return result; } /** * Creates a unary function that invokes `func` with its argument transformed. * * @private * @param {Function} func The function to wrap. * @param {Function} transform The argument transform. * @returns {Function} Returns the new function. */ function overArg(func, transform) { return function(arg) { return func(transform(arg)); }; } /** * Converts `set` to an array of its values. * * @private * @param {Object} set The set to convert. * @returns {Array} Returns the values. */ function setToArray(set) { var index = -1, result = Array(set.size); set.forEach(function(value) { result[++index] = value; }); return result; } /** Used for built-in method references. */ var arrayProto = Array.prototype, funcProto = Function.prototype, objectProto = Object.prototype; /** Used to detect overreaching core-js shims. */ var coreJsData = root['__core-js_shared__']; /** Used to detect methods masquerading as native. */ var maskSrcKey = (function() { var uid = /[^.]+$/.exec(coreJsData && coreJsData.keys && coreJsData.keys.IE_PROTO || ''); return uid ? ('Symbol(src)_1.' + uid) : ''; }()); /** Used to resolve the decompiled source of functions. */ var funcToString = funcProto.toString; /** Used to check objects for own properties. */ var hasOwnProperty = objectProto.hasOwnProperty; /** * Used to resolve the * [`toStringTag`](http://ecma-international.org/ecma-262/7.0/#sec-object.prototype.tostring) * of values. */ var objectToString = objectProto.toString; /** Used to detect if a method is native. */ var reIsNative = RegExp('^' + funcToString.call(hasOwnProperty).replace(reRegExpChar, '\\$&') .replace(/hasOwnProperty|(function).*?(?=\\\()| for .+?(?=\\\])/g, '$1.*?') + '$' ); /** Built-in value references. */ var Symbol = root.Symbol, Uint8Array = root.Uint8Array, propertyIsEnumerable = objectProto.propertyIsEnumerable, splice = arrayProto.splice; /* Built-in method references for those with the same name as other `lodash` methods. */ var nativeKeys = overArg(Object.keys, Object); /* Built-in method references that are verified to be native. */ var DataView = getNative(root, 'DataView'), Map = getNative(root, 'Map'), Promise = getNative(root, 'Promise'), Set = getNative(root, 'Set'), WeakMap = getNative(root, 'WeakMap'), nativeCreate = getNative(Object, 'create'); /** Used to detect maps, sets, and weakmaps. */ var dataViewCtorString = toSource(DataView), mapCtorString = toSource(Map), promiseCtorString = toSource(Promise), setCtorString = toSource(Set), weakMapCtorString = toSource(WeakMap); /** Used to convert symbols to primitives and strings. */ var symbolProto = Symbol ? Symbol.prototype : undefined, symbolValueOf = symbolProto ? symbolProto.valueOf : undefined, symbolToString = symbolProto ? symbolProto.toString : undefined; /** * Creates a hash object. * * @private * @constructor * @param {Array} [entries] The key-value pairs to cache. */ function Hash(entries) { var index = -1, length = entries ? entries.length : 0; this.clear(); while (++index < length) { var entry = entries[index]; this.set(entry[0], entry[1]); } } /** * Removes all key-value entries from the hash. * * @private * @name clear * @memberOf Hash */ function hashClear() { this.__data__ = nativeCreate ? nativeCreate(null) : {}; } /** * Removes `key` and its value from the hash. * * @private * @name delete * @memberOf Hash * @param {Object} hash The hash to modify. * @param {string} key The key of the value to remove. * @returns {boolean} Returns `true` if the entry was removed, else `false`. */ function hashDelete(key) { return this.has(key) && delete this.__data__[key]; } /** * Gets the hash value for `key`. * * @private * @name get * @memberOf Hash * @param {string} key The key of the value to get. * @returns {*} Returns the entry value. */ function hashGet(key) { var data = this.__data__; if (nativeCreate) { var result = data[key]; return result === HASH_UNDEFINED ? undefined : result; } return hasOwnProperty.call(data, key) ? data[key] : undefined; } /** * Checks if a hash value for `key` exists. * * @private * @name has * @memberOf Hash * @param {string} key The key of the entry to check. * @returns {boolean} Returns `true` if an entry for `key` exists, else `false`. */ function hashHas(key) { var data = this.__data__; return nativeCreate ? data[key] !== undefined : hasOwnProperty.call(data, key); } /** * Sets the hash `key` to `value`. * * @private * @name set * @memberOf Hash * @param {string} key The key of the value to set. * @param {*} value The value to set. * @returns {Object} Returns the hash instance. */ function hashSet(key, value) { var data = this.__data__; data[key] = (nativeCreate && value === undefined) ? HASH_UNDEFINED : value; return this; } // Add methods to `Hash`. Hash.prototype.clear = hashClear; Hash.prototype['delete'] = hashDelete; Hash.prototype.get = hashGet; Hash.prototype.has = hashHas; Hash.prototype.set = hashSet; /** * Creates an list cache object. * * @private * @constructor * @param {Array} [entries] The key-value pairs to cache. */ function ListCache(entries) { var index = -1, length = entries ? entries.length : 0; this.clear(); while (++index < length) { var entry = entries[index]; this.set(entry[0], entry[1]); } } /** * Removes all key-value entries from the list cache. * * @private * @name clear * @memberOf ListCache */ function listCacheClear() { this.__data__ = []; } /** * Removes `key` and its value from the list cache. * * @private * @name delete * @memberOf ListCache * @param {string} key The key of the value to remove. * @returns {boolean} Returns `true` if the entry was removed, else `false`. */ function listCacheDelete(key) { var data = this.__data__, index = assocIndexOf(data, key); if (index < 0) { return false; } var lastIndex = data.length - 1; if (index == lastIndex) { data.pop(); } else { splice.call(data, index, 1); } return true; } /** * Gets the list cache value for `key`. * * @private * @name get * @memberOf ListCache * @param {string} key The key of the value to get. * @returns {*} Returns the entry value. */ function listCacheGet(key) { var data = this.__data__, index = assocIndexOf(data, key); return index < 0 ? undefined : data[index][1]; } /** * Checks if a list cache value for `key` exists. * * @private * @name has * @memberOf ListCache * @param {string} key The key of the entry to check. * @returns {boolean} Returns `true` if an entry for `key` exists, else `false`. */ function listCacheHas(key) { return assocIndexOf(this.__data__, key) > -1; } /** * Sets the list cache `key` to `value`. * * @private * @name set * @memberOf ListCache * @param {string} key The key of the value to set. * @param {*} value The value to set. * @returns {Object} Returns the list cache instance. */ function listCacheSet(key, value) { var data = this.__data__, index = assocIndexOf(data, key); if (index < 0) { data.push([key, value]); } else { data[index][1] = value; } return this; } // Add methods to `ListCache`. ListCache.prototype.clear = listCacheClear; ListCache.prototype['delete'] = listCacheDelete; ListCache.prototype.get = listCacheGet; ListCache.prototype.has = listCacheHas; ListCache.prototype.set = listCacheSet; /** * Creates a map cache object to store key-value pairs. * * @private * @constructor * @param {Array} [entries] The key-value pairs to cache. */ function MapCache(entries) { var index = -1, length = entries ? entries.length : 0; this.clear(); while (++index < length) { var entry = entries[index]; this.set(entry[0], entry[1]); } } /** * Removes all key-value entries from the map. * * @private * @name clear * @memberOf MapCache */ function mapCacheClear() { this.__data__ = { 'hash': new Hash, 'map': new (Map || ListCache), 'string': new Hash }; } /** * Removes `key` and its value from the map. * * @private * @name delete * @memberOf MapCache * @param {string} key The key of the value to remove. * @returns {boolean} Returns `true` if the entry was removed, else `false`. */ function mapCacheDelete(key) { return getMapData(this, key)['delete'](key); } /** * Gets the map value for `key`. * * @private * @name get * @memberOf MapCache * @param {string} key The key of the value to get. * @returns {*} Returns the entry value. */ function mapCacheGet(key) { return getMapData(this, key).get(key); } /** * Checks if a map value for `key` exists. * * @private * @name has * @memberOf MapCache * @param {string} key The key of the entry to check. * @returns {boolean} Returns `true` if an entry for `key` exists, else `false`. */ function mapCacheHas(key) { return getMapData(this, key).has(key); } /** * Sets the map `key` to `value`. * * @private * @name set * @memberOf MapCache * @param {string} key The key of the value to set. * @param {*} value The value to set. * @returns {Object} Returns the map cache instance. */ function mapCacheSet(key, value) { getMapData(this, key).set(key, value); return this; } // Add methods to `MapCache`. MapCache.prototype.clear = mapCacheClear; MapCache.prototype['delete'] = mapCacheDelete; MapCache.prototype.get = mapCacheGet; MapCache.prototype.has = mapCacheHas; MapCache.prototype.set = mapCacheSet; /** * * Creates an array cache object to store unique values. * * @private * @constructor * @param {Array} [values] The values to cache. */ function SetCache(values) { var index = -1, length = values ? values.length : 0; this.__data__ = new MapCache; while (++index < length) { this.add(values[index]); } } /** * Adds `value` to the array cache. * * @private * @name add * @memberOf SetCache * @alias push * @param {*} value The value to cache. * @returns {Object} Returns the cache instance. */ function setCacheAdd(value) { this.__data__.set(value, HASH_UNDEFINED); return this; } /** * Checks if `value` is in the array cache. * * @private * @name has * @memberOf SetCache * @param {*} value The value to search for. * @returns {number} Returns `true` if `value` is found, else `false`. */ function setCacheHas(value) { return this.__data__.has(value); } // Add methods to `SetCache`. SetCache.prototype.add = SetCache.prototype.push = setCacheAdd; SetCache.prototype.has = setCacheHas; /** * Creates a stack cache object to store key-value pairs. * * @private * @constructor * @param {Array} [entries] The key-value pairs to cache. */ function Stack(entries) { this.__data__ = new ListCache(entries); } /** * Removes all key-value entries from the stack. * * @private * @name clear * @memberOf Stack */ function stackClear() { this.__data__ = new ListCache; } /** * Removes `key` and its value from the stack. * * @private * @name delete * @memberOf Stack * @param {string} key The key of the value to remove. * @returns {boolean} Returns `true` if the entry was removed, else `false`. */ function stackDelete(key) { return this.__data__['delete'](key); } /** * Gets the stack value for `key`. * * @private * @name get * @memberOf Stack * @param {string} key The key of the value to get. * @returns {*} Returns the entry value. */ function stackGet(key) { return this.__data__.get(key); } /** * Checks if a stack value for `key` exists. * * @private * @name has * @memberOf Stack * @param {string} key The key of the entry to check. * @returns {boolean} Returns `true` if an entry for `key` exists, else `false`. */ function stackHas(key) { return this.__data__.has(key); } /** * Sets the stack `key` to `value`. * * @private * @name set * @memberOf Stack * @param {string} key The key of the value to set. * @param {*} value The value to set. * @returns {Object} Returns the stack cache instance. */ function stackSet(key, value) { var cache = this.__data__; if (cache instanceof ListCache) { var pairs = cache.__data__; if (!Map || (pairs.length < LARGE_ARRAY_SIZE - 1)) { pairs.push([key, value]); return this; } cache = this.__data__ = new MapCache(pairs); } cache.set(key, value); return this; } // Add methods to `Stack`. Stack.prototype.clear = stackClear; Stack.prototype['delete'] = stackDelete; Stack.prototype.get = stackGet; Stack.prototype.has = stackHas; Stack.prototype.set = stackSet; /** * Creates an array of the enumerable property names of the array-like `value`. * * @private * @param {*} value The value to query. * @param {boolean} inherited Specify returning inherited property names. * @returns {Array} Returns the array of property names. */ //创建一个array-like对象的自身键组成的数组 function arrayLikeKeys(value, inherited) { // Safari 8.1 makes `arguments.callee` enumerable in strict mode. // Safari 9 makes `arguments.length` enumerable in strict mode. var result = (isArray(value) || isArguments(value)) ? baseTimes(value.length, String) : []; //如果value是数组或者arguments对象，那么结果数组就是调用baseTimes的结果 //否则是空数组 var length = result.length,//结果数组的长度 skipIndexes = !!length;//是否跳过index索引属性 for (var key in value) {//用for in语句循环value，将符合条件的自身属性push到结果数组里 if ((inherited || hasOwnProperty.call(value, key)) && !(skipIndexes && (key == 'length' || isIndex(key, length)))) { //inherited指定了继承属性名或者是自身属性，并且满足是否跳过index索引属性的要求 result.push(key); } } return result; } /** * Gets the index at which the `key` is found in `array` of key-value pairs. * * @private * @param {Array} array The array to inspect. * @param {*} key The key to search for. * @returns {number} Returns the index of the matched value, else `-1`. */ function assocIndexOf(array, key) { var length = array.length; while (length--) { if (eq(array[length][0], key)) { return length; } } return -1; } /** * The base implementation of `_.forEach` without support for iteratee shorthands. * * @private * @param {Array|Object} collection The collection to iterate over. * @param {Function} iteratee The function invoked per iteration. * @returns {Array|Object} Returns `collection`. */ //forEach基础实现 var baseEach = createBaseEach(baseForOwn); /** * The base implementation of `baseForOwn` which iterates over `object` * properties returned by `keysFunc` and invokes `iteratee` for each property. * Iteratee functions may exit iteration early by explicitly returning `false`. * * @private * @param {Object} object The object to iterate over. * @param {Function} iteratee The function invoked per iteration. * @param {Function} keysFunc The function to get the keys of `object`. * @returns {Object} Returns `object`. */ //创建循环对象自身属性的基础方法 var baseFor = createBaseFor(); /** * The base implementation of `_.forOwn` without support for iteratee shorthands. * * @private * @param {Object} object The object to iterate over. * @param {Function} iteratee The function invoked per iteration. * @returns {Object} Returns `object`. */ //forOwn的基础实现，循环对象自身属性 function baseForOwn(object, iteratee) { return object && baseFor(object, iteratee, keys);//调用baseFor处理 } /** * The base implementation of `_.get` without support for default values. * * @private * @param {Object} object The object to query. * @param {Array|string} path The path of the property to get. * @returns {*} Returns the resolved value. */ function baseGet(object, path) { path = isKey(path, object) ? [path] : castPath(path); var index = 0, length = path.length; while (object != null && index < length) { object = object[toKey(path[index++])]; } return (index && index == length) ? object : undefined; } /** * The base implementation of `getTag`. * * @private * @param {*} value The value to query. * @returns {string} Returns the `toStringTag`. */ function baseGetTag(value) { return objectToString.call(value); } /** * The base implementation of `_.hasIn` without support for deep paths. * * @private * @param {Object} [object] The object to query. * @param {Array|string} key The key to check. * @returns {boolean} Returns `true` if `key` exists, else `false`. */ function baseHasIn(object, key) { return object != null && key in Object(object); } /** * The base implementation of `_.isEqual` which supports partial comparisons * and tracks traversed objects. * * @private * @param {*} value The value to compare. * @param {*} other The other value to compare. * @param {Function} [customizer] The function to customize comparisons. * @param {boolean} [bitmask] The bitmask of comparison flags. * The bitmask may be composed of the following flags: * 1 - Unordered comparison * 2 - Partial comparison * @param {Object} [stack] Tracks traversed `value` and `other` objects. * @returns {boolean} Returns `true` if the values are equivalent, else `false`. */ function baseIsEqual(value, other, customizer, bitmask, stack) { if (value === other) { return true; } if (value == null || other == null || (!isObject(value) && !isObjectLike(other))) { return value !== value && other !== other; } return baseIsEqualDeep(value, other, baseIsEqual, customizer, bitmask, stack); } /** * A specialized version of `baseIsEqual` for arrays and objects which performs * deep comparisons and tracks traversed objects enabling objects with circular * references to be compared. * * @private * @param {Object} object The object to compare. * @param {Object} other The other object to compare. * @param {Function} equalFunc The function to determine equivalents of values. * @param {Function} [customizer] The function to customize comparisons. * @param {number} [bitmask] The bitmask of comparison flags. See `baseIsEqual` * for more details. * @param {Object} [stack] Tracks traversed `object` and `other` objects. * @returns {boolean} Returns `true` if the objects are equivalent, else `false`. */ function baseIsEqualDeep(object, other, equalFunc, customizer, bitmask, stack) { var objIsArr = isArray(object), othIsArr = isArray(other), objTag = arrayTag, othTag = arrayTag; if (!objIsArr) { objTag = getTag(object); objTag = objTag == argsTag ? objectTag : objTag; } if (!othIsArr) { othTag = getTag(other); othTag = othTag == argsTag ? objectTag : othTag; } var objIsObj = objTag == objectTag && !isHostObject(object), othIsObj = othTag == objectTag && !isHostObject(other), isSameTag = objTag == othTag; if (isSameTag && !objIsObj) { stack || (stack = new Stack); return (objIsArr || isTypedArray(object)) ? equalArrays(object, other, equalFunc, customizer, bitmask, stack) : equalByTag(object, other, objTag, equalFunc, customizer, bitmask, stack); } if (!(bitmask & PARTIAL_COMPARE_FLAG)) { var objIsWrapped = objIsObj && hasOwnProperty.call(object, '__wrapped__'), othIsWrapped = othIsObj && hasOwnProperty.call(other, '__wrapped__'); if (objIsWrapped || othIsWrapped) { var objUnwrapped = objIsWrapped ? object.value() : object, othUnwrapped = othIsWrapped ? other.value() : other; stack || (stack = new Stack); return equalFunc(objUnwrapped, othUnwrapped, customizer, bitmask, stack); } } if (!isSameTag) { return false; } stack || (stack = new Stack); return equalObjects(object, other, equalFunc, customizer, bitmask, stack); } /** * The base implementation of `_.isMatch` without support for iteratee shorthands. * * @private * @param {Object} object The object to inspect. * @param {Object} source The object of property values to match. * @param {Array} matchData The property names, values, and compare flags to match. * @param {Function} [customizer] The function to customize comparisons. * @returns {boolean} Returns `true` if `object` is a match, else `false`. */ function baseIsMatch(object, source, matchData, customizer) { var index = matchData.length, length = index, noCustomizer = !customizer; if (object == null) { return !length; } object = Object(object); while (index--) { var data = matchData[index]; if ((noCustomizer && data[2]) ? data[1] !== object[data[0]] : !(data[0] in object) ) { return false; } } while (++index < length) { data = matchData[index]; var key = data[0], objValue = object[key], srcValue = data[1]; if (noCustomizer && data[2]) { if (objValue === undefined && !(key in object)) { return false; } } else { var stack = new Stack; if (customizer) { var result = customizer(objValue, srcValue, key, object, source, stack); } if (!(result === undefined ? baseIsEqual(srcValue, objValue, customizer, UNORDERED_COMPARE_FLAG | PARTIAL_COMPARE_FLAG, stack) : result )) { return false; } } } return true; } /** * The base implementation of `_.isNative` without bad shim checks. * * @private * @param {*} value The value to check. * @returns {boolean} Returns `true` if `value` is a native function, * else `false`. */ function baseIsNative(value) { if (!isObject(value) || isMasked(value)) { return false; } var pattern = (isFunction(value) || isHostObject(value)) ? reIsNative : reIsHostCtor; return pattern.test(toSource(value)); } /** * The base implementation of `_.isTypedArray` without Node.js optimizations. * * @private * @param {*} value The value to check. * @returns {boolean} Returns `true` if `value` is a typed array, else `false`. */ function baseIsTypedArray(value) { return isObjectLike(value) && isLength(value.length) && !!typedArrayTags[objectToString.call(value)]; } /** * The base implementation of `_.iteratee`. * * @private * @param {*} [value=_.identity] The value to convert to an iteratee. * @returns {Function} Returns the iteratee. */ function baseIteratee(value) { // Don't store the `typeof` result in a variable to avoid a JIT bug in Safari 9. // See https://bugs.webkit.org/show_bug.cgi?id=156034 for more details. if (typeof value == 'function') { return value; } if (value == null) { return identity; } if (typeof value == 'object') { return isArray(value) ? baseMatchesProperty(value[0], value[1]) : baseMatches(value); } return property(value); } /** * The base implementation of `_.keys` which doesn't treat sparse arrays as dense. * * @private * @param {Object} object The object to query. * @returns {Array} Returns the array of property names. */ //keys的基础实现，创建对象自身属性组成的数组 function baseKeys(object) { if (!isPrototype(object)) {//如果object是一个prototype，返回nativeKeys调用结果 return nativeKeys(object); } var result = [];//结果数组 for (var key in Object(object)) {//for in循环object if (hasOwnProperty.call(object, key) && key != 'constructor') { //如果key是object自身key并且不是constructor属性，就push进结果数组 result.push(key); } } return result; } /** * The base implementation of `_.map` without support for iteratee shorthands. * * @private * @param {Array|Object} collection The collection to iterate over. * @param {Function} iteratee The function invoked per iteration. * @returns {Array} Returns the new mapped array. */ //_.map基础实现，可支持数组和对象的遍历 function baseMap(collection, iteratee) { var index = -1,//循环索引 result = isArrayLike(collection) ? Array(collection.length) : []; //判断collection是array-like还是对象，然后根据类型初始化对应的结果数组 baseEach(collection, function(value, key, collection) { //调用baseEach遍历collection，调用iteratee处理当前元素后存入结果数组 result[++index] = iteratee(value, key, collection); }); return result; } /** * The base implementation of `_.matches` which doesn't clone `source`. * * @private * @param {Object} source The object of property values to match. * @returns {Function} Returns the new spec function. */ function baseMatches(source) { var matchData = getMatchData(source); if (matchData.length == 1 && matchData[0][2]) { return matchesStrictComparable(matchData[0][0], matchData[0][1]); } return function(object) { return object === source || baseIsMatch(object, source, matchData); }; } /** * The base implementation of `_.matchesProperty` which doesn't clone `srcValue`. * * @private * @param {string} path The path of the property to get. * @param {*} srcValue The value to match. * @returns {Function} Returns the new spec function. */ function baseMatchesProperty(path, srcValue) { if (isKey(path) && isStrictComparable(srcValue)) { return matchesStrictComparable(toKey(path), srcValue); } return function(object) { var objValue = get(object, path); return (objValue === undefined && objValue === srcValue) ? hasIn(object, path) : baseIsEqual(srcValue, objValue, undefined, UNORDERED_COMPARE_FLAG | PARTIAL_COMPARE_FLAG); }; } /** * The base implementation of `_.orderBy` without param guards. * * @private * @param {Array|Object} collection The collection to iterate over. * @param {Function[]|Object[]|string[]} iteratees The iteratees to sort by. * @param {string[]} orders The sort orders of `iteratees`. * @returns {Array} Returns the new sorted array. */ //_.orderBy的基础实现 function baseOrderBy(collection, iteratees, orders) { var index = -1;//循环索引 iteratees = arrayMap(iteratees.length ? iteratees : [identity], baseUnary(baseIteratee)); //判断iteratees的长度，如果没有就使用identity直接返回接收的第一个参数。 //然后调用arrayMap遍历iteratees，将所有iteratee都传递给baseIteratee处理成function，因为原始传递的iteratee可能只是个字符串路径数组之类的值 var result = baseMap(collection, function(value, key, collection) { //调用baseMap遍历collection，在遍历器里调用arrayMap遍历iteratees，根据它生成criteria的标准以便后面比较排序 var criteria = arrayMap(iteratees, function(iteratee) { return iteratee(value); }); return { 'criteria': criteria, 'index': ++index, 'value': value }; //新的collection的元素为上面这个对象，遍历器处理结果的数组，索引，和原始值 }); return baseSortBy(result, function(object, other) { return compareMultiple(object, other, orders); }); //调用baseSortBy遍历处理好的criteria标准，为result排序，根据标准criteria排序后再将result原始元素替换回去 } /** * A specialized version of `baseProperty` which supports deep paths. * * @private * @param {Array|string} path The path of the property to get. * @returns {Function} Returns the new accessor function. */ function basePropertyDeep(path) { return function(object) { return baseGet(object, path); }; } /** * The base implementation of `_.toString` which doesn't convert nullish * values to empty strings. * * @private * @param {*} value The value to process. * @returns {string} Returns the string. */ function baseToString(value) { // Exit early for strings to avoid a performance hit in some environments. if (typeof value == 'string') { return value; } if (isSymbol(value)) { return symbolToString ? symbolToString.call(value) : ''; } var result = (value + ''); return (result == '0' && (1 / value) == -INFINITY) ? '-0' : result; } /** * Casts `value` to a path array if it's not one. * * @private * @param {*} value The value to inspect. * @returns {Array} Returns the cast property path array. */ function castPath(value) { return isArray(value) ? value : stringToPath(value); } /** * Compares values to sort them in ascending order. * * @private * @param {*} value The value to compare. * @param {*} other The other value to compare. * @returns {number} Returns the sort order indicator for `value`. */ //升序排序比较函数 function compareAscending(value, other) { if (value !== other) { var valIsDefined = value !== undefined, valIsNull = value === null, valIsReflexive = value === value, valIsSymbol = isSymbol(value); var othIsDefined = other !== undefined, othIsNull = other === null, othIsReflexive = other === other, othIsSymbol = isSymbol(other); if ((!othIsNull && !othIsSymbol && !valIsSymbol && value > other) || (valIsSymbol && othIsDefined && othIsReflexive && !othIsNull && !othIsSymbol) || (valIsNull && othIsDefined && othIsReflexive) || (!valIsDefined && othIsReflexive) || !valIsReflexive) { return 1; } if ((!valIsNull && !valIsSymbol && !othIsSymbol && value < other) || (othIsSymbol && valIsDefined && valIsReflexive && !valIsNull && !valIsSymbol) || (othIsNull && valIsDefined && valIsReflexive) || (!othIsDefined && valIsReflexive) || !othIsReflexive) { return -1; } } return 0; } /** * Used by `_.orderBy` to compare multiple properties of a value to another * and stable sort them. * * If `orders` is unspecified, all values are sorted in ascending order. Otherwise, * specify an order of "desc" for descending or "asc" for ascending sort order * of corresponding values. * * @private * @param {Object} object The object to compare. * @param {Object} other The other object to compare. * @param {boolean[]|string[]} orders The order to sort by for each property. * @returns {number} Returns the sort order indicator for `object`. */ //被orderBy方法调用来比较一个值和另一个值的多个属性并且稳定排序 //如果没有指定orders参数，就默认升序 function compareMultiple(object, other, orders) { var index = -1,//循环索引 objCriteria = object.criteria,//object的经过iteratee处理过的标准值 othCriteria = other.criteria,//other的经过iteratee处理过的标准值 length = objCriteria.length,//object标准值长度 ordersLength = orders.length;//orders长度 while (++index < length) {//遍历object标准值数组 var result = compareAscending(objCriteria[index], othCriteria[index]); //调用升序排序比较函数比较出结果 if (result) { if (index >= ordersLength) { return result; } var order = orders[index]; return result * (order == 'desc' ? -1 : 1); } } // Fixes an `Array#sort` bug in the JS engine embedded in Adobe applications // that causes it, under certain circumstances, to provide the same value for // `object` and `other`. See https://github.com/jashkenas/underscore/pull/1247 // for more details. // // This also ensures a stable sort in V8 and other engines. // See https://bugs.chromium.org/p/v8/issues/detail?id=90 for more details. return object.index - other.index;//如果result结果是0，则稳定排序的元素位置 } /** * Creates a `baseEach` or `baseEachRight` function. * * @private * @param {Function} eachFunc The function to iterate over a collection. * @param {boolean} [fromRight] Specify iterating from right to left. * @returns {Function} Returns the new base function. */ //创建一个baseEach或者baseEachRight方法 function createBaseEach(eachFunc, fromRight) { return function(collection, iteratee) { if (collection == null) {//如果collection是空，直接返回 return collection; } if (!isArrayLike(collection)) {//如果collection不是array-like对象，就用eachFunc return eachFunc(collection, iteratee); } var length = collection.length,//collection长度 index = fromRight ? length : -1,//循环索引，如果fromRight就从结尾开始，否则从开头开始 iterable = Object(collection); while ((fromRight ? index-- : ++index < length)) {//循环，如果iteratee返回false，跳出循环 if (iteratee(iterable[index], index, iterable) === false) { break; } } return collection; }; } /** * Creates a base function for methods like `_.forIn` and `_.forOwn`. * * @private * @param {boolean} [fromRight] Specify iterating from right to left. * @returns {Function} Returns the new base function. */ //类似forIn或者forOwn方法，用于循环对象的属性 function createBaseFor(fromRight) { return function(object, iteratee, keysFunc) { var index = -1,//循环索引 iterable = Object(object), props = keysFunc(object),//对象的键组成的数组 length = props.length;//键数组的长度 while (length--) {//循环键数组 var key = props[fromRight ? length : ++index]; if (iteratee(iterable[key], key, iterable) === false) { //如果iteratee调用后返回false，就跳出循环 break; } } return object; }; } /** * A specialized version of `baseIsEqualDeep` for arrays with support for * partial deep comparisons. * * @private * @param {Array} array The array to compare. * @param {Array} other The other array to compare. * @param {Function} equalFunc The function to determine equivalents of values. * @param {Function} customizer The function to customize comparisons. * @param {number} bitmask The bitmask of comparison flags. See `baseIsEqual` * for more details. * @param {Object} stack Tracks traversed `array` and `other` objects. * @returns {boolean} Returns `true` if the arrays are equivalent, else `false`. */ function equalArrays(array, other, equalFunc, customizer, bitmask, stack) { var isPartial = bitmask & PARTIAL_COMPARE_FLAG, arrLength = array.length, othLength = other.length; if (arrLength != othLength && !(isPartial && othLength > arrLength)) { return false; } // Assume cyclic values are equal. var stacked = stack.get(array); if (stacked && stack.get(other)) { return stacked == other; } var index = -1, result = true, seen = (bitmask & UNORDERED_COMPARE_FLAG) ? new SetCache : undefined; stack.set(array, other); stack.set(other, array); // Ignore non-index properties. while (++index < arrLength) { var arrValue = array[index], othValue = other[index]; if (customizer) { var compared = isPartial ? customizer(othValue, arrValue, index, other, array, stack) : customizer(arrValue, othValue, index, array, other, stack); } if (compared !== undefined) { if (compared) { continue; } result = false; break; } // Recursively compare arrays (susceptible to call stack limits). if (seen) { if (!arraySome(other, function(othValue, othIndex) { if (!seen.has(othIndex) && (arrValue === othValue || equalFunc(arrValue, othValue, customizer, bitmask, stack))) { return seen.add(othIndex); } })) { result = false; break; } } else if (!( arrValue === othValue || equalFunc(arrValue, othValue, customizer, bitmask, stack) )) { result = false; break; } } stack['delete'](array); stack['delete'](other); return result; } /** * A specialized version of `baseIsEqualDeep` for comparing objects of * the same `toStringTag`. * * **Note:** This function only supports comparing values with tags of * `Boolean`, `Date`, `Error`, `Number`, `RegExp`, or `String`. * * @private * @param {Object} object The object to compare. * @param {Object} other The other object to compare. * @param {string} tag The `toStringTag` of the objects to compare. * @param {Function} equalFunc The function to determine equivalents of values. * @param {Function} customizer The function to customize comparisons. * @param {number} bitmask The bitmask of comparison flags. See `baseIsEqual` * for more details. * @param {Object} stack Tracks traversed `object` and `other` objects. * @returns {boolean} Returns `true` if the objects are equivalent, else `false`. */ function equalByTag(object, other, tag, equalFunc, customizer, bitmask, stack) { switch (tag) { case dataViewTag: if ((object.byteLength != other.byteLength) || (object.byteOffset != other.byteOffset)) { return false; } object = object.buffer; other = other.buffer; case arrayBufferTag: if ((object.byteLength != other.byteLength) || !equalFunc(new Uint8Array(object), new Uint8Array(other))) { return false; } return true; case boolTag: case dateTag: case numberTag: // Coerce booleans to `1` or `0` and dates to milliseconds. // Invalid dates are coerced to `NaN`. return eq(+object, +other); case errorTag: return object.name == other.name && object.message == other.message; case regexpTag: case stringTag: // Coerce regexes to strings and treat strings, primitives and objects, // as equal. See http://www.ecma-international.org/ecma-262/7.0/#sec-regexp.prototype.tostring // for more details. return object == (other + ''); case mapTag: var convert = mapToArray; case setTag: var isPartial = bitmask & PARTIAL_COMPARE_FLAG; convert || (convert = setToArray); if (object.size != other.size && !isPartial) { return false; } // Assume cyclic values are equal. var stacked = stack.get(object); if (stacked) { return stacked == other; } bitmask |= UNORDERED_COMPARE_FLAG; // Recursively compare objects (susceptible to call stack limits). stack.set(object, other); var result = equalArrays(convert(object), convert(other), equalFunc, customizer, bitmask, stack); stack['delete'](object); return result; case symbolTag: if (symbolValueOf) { return symbolValueOf.call(object) == symbolValueOf.call(other); } } return false; } /** * A specialized version of `baseIsEqualDeep` for objects with support for * partial deep comparisons. * * @private * @param {Object} object The object to compare. * @param {Object} other The other object to compare. * @param {Function} equalFunc The function to determine equivalents of values. * @param {Function} customizer The function to customize comparisons. * @param {number} bitmask The bitmask of comparison flags. See `baseIsEqual` * for more details. * @param {Object} stack Tracks traversed `object` and `other` objects. * @returns {boolean} Returns `true` if the objects are equivalent, else `false`. */ function equalObjects(object, other, equalFunc, customizer, bitmask, stack) { var isPartial = bitmask & PARTIAL_COMPARE_FLAG, objProps = keys(object), objLength = objProps.length, othProps = keys(other), othLength = othProps.length; if (objLength != othLength && !isPartial) { return false; } var index = objLength; while (index--) { var key = objProps[index]; if (!(isPartial ? key in other : hasOwnProperty.call(other, key))) { return false; } } // Assume cyclic values are equal. var stacked = stack.get(object); if (stacked && stack.get(other)) { return stacked == other; } var result = true; stack.set(object, other); stack.set(other, object); var skipCtor = isPartial; while (++index < objLength) { key = objProps[index]; var objValue = object[key], othValue = other[key]; if (customizer) { var compared = isPartial ? customizer(othValue, objValue, key, other, object, stack) : customizer(objValue, othValue, key, object, other, stack); } // Recursively compare objects (susceptible to call stack limits). if (!(compared === undefined ? (objValue === othValue || equalFunc(objValue, othValue, customizer, bitmask, stack)) : compared )) { result = false; break; } skipCtor || (skipCtor = key == 'constructor'); } if (result && !skipCtor) { var objCtor = object.constructor, othCtor = other.constructor; // Non `Object` object instances with different constructors are not equal. if (objCtor != othCtor && ('constructor' in object && 'constructor' in other) && !(typeof objCtor == 'function' && objCtor instanceof objCtor && typeof othCtor == 'function' && othCtor instanceof othCtor)) { result = false; } } stack['delete'](object); stack['delete'](other); return result; } /** * Gets the data for `map`. * * @private * @param {Object} map The map to query. * @param {string} key The reference key. * @returns {*} Returns the map data. */ function getMapData(map, key) { var data = map.__data__; return isKeyable(key) ? data[typeof key == 'string' ? 'string' : 'hash'] : data.map; } /** * Gets the property names, values, and compare flags of `object`. * * @private * @param {Object} object The object to query. * @returns {Array} Returns the match data of `object`. */ function getMatchData(object) { var result = keys(object), length = result.length; while (length--) { var key = result[length], value = object[key]; result[length] = [key, value, isStrictComparable(value)]; } return result; } /** * Gets the native function at `key` of `object`. * * @private * @param {Object} object The object to query. * @param {string} key The key of the method to get. * @returns {*} Returns the function if it's native, else `undefined`. */ function getNative(object, key) { var value = getValue(object, key); return baseIsNative(value) ? value : undefined; } /** * Gets the `toStringTag` of `value`. * * @private * @param {*} value The value to query. * @returns {string} Returns the `toStringTag`. */ var getTag = baseGetTag; // Fallback for data views, maps, sets, and weak maps in IE 11, // for data views in Edge < 14, and promises in Node.js. if ((DataView && getTag(new DataView(new ArrayBuffer(1))) != dataViewTag) || (Map && getTag(new Map) != mapTag) || (Promise && getTag(Promise.resolve()) != promiseTag) || (Set && getTag(new Set) != setTag) || (WeakMap && getTag(new WeakMap) != weakMapTag)) { getTag = function(value) { var result = objectToString.call(value), Ctor = result == objectTag ? value.constructor : undefined, ctorString = Ctor ? toSource(Ctor) : undefined; if (ctorString) { switch (ctorString) { case dataViewCtorString: return dataViewTag; case mapCtorString: return mapTag; case promiseCtorString: return promiseTag; case setCtorString: return setTag; case weakMapCtorString: return weakMapTag; } } return result; }; } /** * Checks if `path` exists on `object`. * * @private * @param {Object} object The object to query. * @param {Array|string} path The path to check. * @param {Function} hasFunc The function to check properties. * @returns {boolean} Returns `true` if `path` exists, else `false`. */ function hasPath(object, path, hasFunc) { path = isKey(path, object) ? [path] : castPath(path); var result, index = -1, length = path.length; while (++index < length) { var key = toKey(path[index]); if (!(result = object != null && hasFunc(object, key))) { break; } object = object[key]; } if (result) { return result; } var length = object ? object.length : 0; return !!length && isLength(length) && isIndex(key, length) && (isArray(object) || isArguments(object)); } /** * Checks if `value` is a valid array-like index. * * @private * @param {*} value The value to check. * @param {number} [length=MAX_SAFE_INTEGER] The upper bounds of a valid index. * @returns {boolean} Returns `true` if `value` is a valid index, else `false`. */ //判断一个值是否是有效的array-like对象的索引 function isIndex(value, length) { length = length == null ? MAX_SAFE_INTEGER : length; return !!length && (typeof value == 'number' || reIsUint.test(value)) && (value > -1 && value % 1 == 0 && value < length); } /** * Checks if `value` is a property name and not a property path. * * @private * @param {*} value The value to check. * @param {Object} [object] The object to query keys on. * @returns {boolean} Returns `true` if `value` is a property name, else `false`. */ function isKey(value, object) { if (isArray(value)) { return false; } var type = typeof value; if (type == 'number' || type == 'symbol' || type == 'boolean' || value == null || isSymbol(value)) { return true; } return reIsPlainProp.test(value) || !reIsDeepProp.test(value) || (object != null && value in Object(object)); } /** * Checks if `value` is suitable for use as unique object key. * * @private * @param {*} value The value to check. * @returns {boolean} Returns `true` if `value` is suitable, else `false`. */ function isKeyable(value) { var type = typeof value; return (type == 'string' || type == 'number' || type == 'symbol' || type == 'boolean') ? (value !== '__proto__') : (value === null); } /** * Checks if `func` has its source masked. * * @private * @param {Function} func The function to check. * @returns {boolean} Returns `true` if `func` is masked, else `false`. */ function isMasked(func) { return !!maskSrcKey && (maskSrcKey in func); } /** * Checks if `value` is likely a prototype object. * * @private * @param {*} value The value to check. * @returns {boolean} Returns `true` if `value` is a prototype, else `false`. */ //判断一个值是否是一个prototype对象 function isPrototype(value) { var Ctor = value && value.constructor, proto = (typeof Ctor == 'function' && Ctor.prototype) || objectProto; return value === proto; } /** * Checks if `value` is suitable for strict equality comparisons, i.e. `===`. * * @private * @param {*} value The value to check. * @returns {boolean} Returns `true` if `value` if suitable for strict * equality comparisons, else `false`. */ function isStrictComparable(value) { return value === value && !isObject(value); } /** * A specialized version of `matchesProperty` for source values suitable * for strict equality comparisons, i.e. `===`. * * @private * @param {string} key The key of the property to get. * @param {*} srcValue The value to match. * @returns {Function} Returns the new spec function. */ function matchesStrictComparable(key, srcValue) { return function(object) { if (object == null) { return false; } return object[key] === srcValue && (srcValue !== undefined || (key in Object(object))); }; } /** * Converts `string` to a property path array. * * @private * @param {string} string The string to convert. * @returns {Array} Returns the property path array. */ var stringToPath = memoize(function(string) { string = toString(string); var result = []; if (reLeadingDot.test(string)) { result.push(''); } string.replace(rePropName, function(match, number, quote, string) { result.push(quote ? string.replace(reEscapeChar, '$1') : (number || match)); }); return result; }); /** * Converts `value` to a string key if it's not a string or symbol. * * @private * @param {*} value The value to inspect. * @returns {string|symbol} Returns the key. */ function toKey(value) { if (typeof value == 'string' || isSymbol(value)) { return value; } var result = (value + ''); return (result == '0' && (1 / value) == -INFINITY) ? '-0' : result; } /** * Converts `func` to its source code. * * @private * @param {Function} func The function to process. * @returns {string} Returns the source code. */ function toSource(func) { if (func != null) { try { return funcToString.call(func); } catch (e) {} try { return (func + ''); } catch (e) {} } return ''; } /** * This method is like `_.sortBy` except that it allows specifying the sort * orders of the iteratees to sort by. If `orders` is unspecified, all values * are sorted in ascending order. Otherwise, specify an order of "desc" for * descending or "asc" for ascending sort order of corresponding values. * * @static * @memberOf _ * @since 4.0.0 * @category Collection * @param {Array|Object} collection The collection to iterate over. * @param {Array[]|Function[]|Object[]|string[]} [iteratees=[_.identity]] * The iteratees to sort by. * @param {string[]} [orders] The sort orders of `iteratees`. * @param- {Object} [guard] Enables use as an iteratee for methods like `_.reduce`. * @returns {Array} Returns the new sorted array. * @example * * var users = [ * { 'user': 'fred', 'age': 48 }, * { 'user': 'barney', 'age': 34 }, * { 'user': 'fred', 'age': 40 }, * { 'user': 'barney', 'age': 36 } * ]; * * // Sort by `user` in ascending order and by `age` in descending order. * _.orderBy(users, ['user', 'age'], ['asc', 'desc']); * // => objects for [['barney', 36], ['barney', 34], ['fred', 48], ['fred', 40]] */ //和sortBy类似，允许指定遍历器遍历的时候排序次序的条件。如果没有指定排序的条件，默认升序。另外，可以指定order参数为desc作为降序，asc作为升序。也可以指定一个比较方法作为排序的条件 function orderBy(collection, iteratees, orders, guard) { if (collection == null) {//如果collection为空，返回空数组 return []; } if (!isArray(iteratees)) {//如果iteratees不是数组，就将其变成一个数组 iteratees = iteratees == null ? [] : [iteratees]; } orders = guard ? undefined : orders; //如果传递了guard，则orderBy作为一个iteratee使用，否则orders参数置空 if (!isArray(orders)) {//如果orders不是数组，就变成一个数组 orders = orders == null ? [] : [orders]; } return baseOrderBy(collection, iteratees, orders);//调用baseOrderBy处理 } /** * Creates a function that memoizes the result of `func`. If `resolver` is * provided, it determines the cache key for storing the result based on the * arguments provided to the memoized function. By default, the first argument * provided to the memoized function is used as the map cache key. The `func` * is invoked with the `this` binding of the memoized function. * * **Note:** The cache is exposed as the `cache` property on the memoized * function. Its creation may be customized by replacing the `_.memoize.Cache` * constructor with one whose instances implement the * [`Map`](http://ecma-international.org/ecma-262/7.0/#sec-properties-of-the-map-prototype-object) * method interface of `delete`, `get`, `has`, and `set`. * * @static * @memberOf _ * @since 0.1.0 * @category Function * @param {Function} func The function to have its output memoized. * @param {Function} [resolver] The function to resolve the cache key. * @returns {Function} Returns the new memoized function. * @example * * var object = { 'a': 1, 'b': 2 }; * var other = { 'c': 3, 'd': 4 }; * * var values = _.memoize(_.values); * values(object); * // => [1, 2] * * values(other); * // => [3, 4] * * object.a = 2; * values(object); * // => [1, 2] * * // Modify the result cache. * values.cache.set(object, ['a', 'b']); * values(object); * // => ['a', 'b'] * * // Replace `_.memoize.Cache`. * _.memoize.Cache = WeakMap; */ function memoize(func, resolver) { if (typeof func != 'function' || (resolver && typeof resolver != 'function')) { throw new TypeError(FUNC_ERROR_TEXT); } var memoized = function() { var args = arguments, key = resolver ? resolver.apply(this, args) : args[0], cache = memoized.cache; if (cache.has(key)) { return cache.get(key); } var result = func.apply(this, args); memoized.cache = cache.set(key, result); return result; }; memoized.cache = new (memoize.Cache || MapCache); return memoized; } // Assign cache to `_.memoize`. memoize.Cache = MapCache; /** * Performs a * [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero) * comparison between two values to determine if they are equivalent. * * @static * @memberOf _ * @since 4.0.0 * @category Lang * @param {*} value The value to compare. * @param {*} other The other value to compare. * @returns {boolean} Returns `true` if the values are equivalent, else `false`. * @example * * var object = { 'a': 1 }; * var other = { 'a': 1 }; * * _.eq(object, object); * // => true * * _.eq(object, other); * // => false * * _.eq('a', 'a'); * // => true * * _.eq('a', Object('a')); * // => false * * _.eq(NaN, NaN); * // => true */ function eq(value, other) { return value === other || (value !== value && other !== other); } /** * Checks if `value` is likely an `arguments` object. * * @static * @memberOf _ * @since 0.1.0 * @category Lang * @param {*} value The value to check. * @returns {boolean} Returns `true` if `value` is an `arguments` object, * else `false`. * @example * * _.isArguments(function() { return arguments; }()); * // => true * * _.isArguments([1, 2, 3]); * // => false */ //判断一个值是否是一个arguments对象 function isArguments(value) { // Safari 8.1 makes `arguments.callee` enumerable in strict mode. return isArrayLikeObject(value) && hasOwnProperty.call(value, 'callee') && (!propertyIsEnumerable.call(value, 'callee') || objectToString.call(value) == argsTag); } /** * Checks if `value` is classified as an `Array` object. * * @static * @memberOf _ * @since 0.1.0 * @category Lang * @param {*} value The value to check. * @returns {boolean} Returns `true` if `value` is an array, else `false`. * @example * * _.isArray([1, 2, 3]); * // => true * * _.isArray(document.body.children); * // => false * * _.isArray('abc'); * // => false * * _.isArray(_.noop); * // => false */ //判断一个值是否是数组 var isArray = Array.isArray; /** * Checks if `value` is array-like. A value is considered array-like if it's * not a function and has a `value.length` that's an integer greater than or * equal to `0` and less than or equal to `Number.MAX_SAFE_INTEGER`. * * @static * @memberOf _ * @since 4.0.0 * @category Lang * @param {*} value The value to check. * @returns {boolean} Returns `true` if `value` is array-like, else `false`. * @example * * _.isArrayLike([1, 2, 3]); * // => true * * _.isArrayLike(document.body.children); * // => true * * _.isArrayLike('abc'); * // => true * * _.isArrayLike(_.noop); * // => false */ //判断一个值是否是array-like对象 function isArrayLike(value) { return value != null && isLength(value.length) && !isFunction(value); } /** * This method is like `_.isArrayLike` except that it also checks if `value` * is an object. * * @static * @memberOf _ * @since 4.0.0 * @category Lang * @param {*} value The value to check. * @returns {boolean} Returns `true` if `value` is an array-like object, * else `false`. * @example * * _.isArrayLikeObject([1, 2, 3]); * // => true * * _.isArrayLikeObject(document.body.children); * // => true * * _.isArrayLikeObject('abc'); * // => false * * _.isArrayLikeObject(_.noop); * // => false */ //判断一个值是不是一个array-like对象同时也是object-like对象 function isArrayLikeObject(value) { return isObjectLike(value) && isArrayLike(value); } /** * Checks if `value` is classified as a `Function` object. * * @static * @memberOf _ * @since 0.1.0 * @category Lang * @param {*} value The value to check. * @returns {boolean} Returns `true` if `value` is a function, else `false`. * @example * * _.isFunction(_); * // => true * * _.isFunction(/abc/); * // => false */ //判断一个值是否是function对象 function isFunction(value) { // The use of `Object#toString` avoids issues with the `typeof` operator // in Safari 8-9 which returns 'object' for typed array and other constructors. var tag = isObject(value) ? objectToString.call(value) : ''; return tag == funcTag || tag == genTag; } /** * Checks if `value` is a valid array-like length. * * **Note:** This method is loosely based on * [`ToLength`](http://ecma-international.org/ecma-262/7.0/#sec-tolength). * * @static * @memberOf _ * @since 4.0.0 * @category Lang * @param {*} value The value to check. * @returns {boolean} Returns `true` if `value` is a valid length, else `false`. * @example * * _.isLength(3); * // => true * * _.isLength(Number.MIN_VALUE); * // => false * * _.isLength(Infinity); * // => false * * _.isLength('3'); * // => false */ //判断一个值是否是一个有效的array-like对象的length属性 function isLength(value) { return typeof value == 'number' && value > -1 && value % 1 == 0 && value <= MAX_SAFE_INTEGER; } /** * Checks if `value` is the * [language type](http://www.ecma-international.org/ecma-262/7.0/#sec-ecmascript-language-types) * of `Object`. (e.g. arrays, functions, objects, regexes, `new Number(0)`, and `new String('')`) * * @static * @memberOf _ * @since 0.1.0 * @category Lang * @param {*} value The value to check. * @returns {boolean} Returns `true` if `value` is an object, else `false`. * @example * * _.isObject({}); * // => true * * _.isObject([1, 2, 3]); * // => true * * _.isObject(_.noop); * // => true * * _.isObject(null); * // => false */ //判断一个值是否是一个语言层面的对象 function isObject(value) { var type = typeof value; return !!value && (type == 'object' || type == 'function'); } /** * Checks if `value` is object-like. A value is object-like if it's not `null` * and has a `typeof` result of "object". * * @static * @memberOf _ * @since 4.0.0 * @category Lang * @param {*} value The value to check. * @returns {boolean} Returns `true` if `value` is object-like, else `false`. * @example * * _.isObjectLike({}); * // => true * * _.isObjectLike([1, 2, 3]); * // => true * * _.isObjectLike(_.noop); * // => false * * _.isObjectLike(null); * // => false */ //判断一个值是否是一个object-like对象 function isObjectLike(value) { return !!value && typeof value == 'object'; } /** * Checks if `value` is classified as a `Symbol` primitive or object. * * @static * @memberOf _ * @since 4.0.0 * @category Lang * @param {*} value The value to check. * @returns {boolean} Returns `true` if `value` is a symbol, else `false`. * @example * * _.isSymbol(Symbol.iterator); * // => true * * _.isSymbol('abc'); * // => false */ function isSymbol(value) { return typeof value == 'symbol' || (isObjectLike(value) && objectToString.call(value) == symbolTag); } /** * Checks if `value` is classified as a typed array. * * @static * @memberOf _ * @since 3.0.0 * @category Lang * @param {*} value The value to check. * @returns {boolean} Returns `true` if `value` is a typed array, else `false`. * @example * * _.isTypedArray(new Uint8Array); * // => true * * _.isTypedArray([]); * // => false */ var isTypedArray = nodeIsTypedArray ? baseUnary(nodeIsTypedArray) : baseIsTypedArray; /** * Converts `value` to a string. An empty string is returned for `null` * and `undefined` values. The sign of `-0` is preserved. * * @static * @memberOf _ * @since 4.0.0 * @category Lang * @param {*} value The value to process. * @returns {string} Returns the string. * @example * * _.toString(null); * // => '' * * _.toString(-0); * // => '-0' * * _.toString([1, 2, 3]); * // => '1,2,3' */ function toString(value) { return value == null ? '' : baseToString(value); } /** * Gets the value at `path` of `object`. If the resolved value is * `undefined`, the `defaultValue` is returned in its place. * * @static * @memberOf _ * @since 3.7.0 * @category Object * @param {Object} object The object to query. * @param {Array|string} path The path of the property to get. * @param {*} [defaultValue] The value returned for `undefined` resolved values. * @returns {*} Returns the resolved value. * @example * * var object = { 'a': [{ 'b': { 'c': 3 } }] }; * * _.get(object, 'a[0].b.c'); * // => 3 * * _.get(object, ['a', '0', 'b', 'c']); * // => 3 * * _.get(object, 'a.b.c', 'default'); * // => 'default' */ function get(object, path, defaultValue) { var result = object == null ? undefined : baseGet(object, path); return result === undefined ? defaultValue : result; } /** * Checks if `path` is a direct or inherited property of `object`. * * @static * @memberOf _ * @since 4.0.0 * @category Object * @param {Object} object The object to query. * @param {Array|string} path The path to check. * @returns {boolean} Returns `true` if `path` exists, else `false`. * @example * * var object = _.create({ 'a': _.create({ 'b': 2 }) }); * * _.hasIn(object, 'a'); * // => true * * _.hasIn(object, 'a.b'); * // => true * * _.hasIn(object, ['a', 'b']); * // => true * * _.hasIn(object, 'b'); * // => false */ function hasIn(object, path) { return object != null && hasPath(object, path, baseHasIn); } /** * Creates an array of the own enumerable property names of `object`. * * **Note:** Non-object values are coerced to objects. See the * [ES spec](http://ecma-international.org/ecma-262/7.0/#sec-object.keys) * for more details. * * @static * @since 0.1.0 * @memberOf _ * @category Object * @param {Object} object The object to query. * @returns {Array} Returns the array of property names. * @example * * function Foo() { * this.a = 1; * this.b = 2; * } * * Foo.prototype.c = 3; * * _.keys(new Foo); * // => ['a', 'b'] (iteration order is not guaranteed) * * _.keys('hi'); * // => ['0', '1'] */ //创建对象的自身属性组成的数组 function keys(object) { return isArrayLike(object) ? arrayLikeKeys(object) : baseKeys(object); //判断object，如果是array-like对象，调用arrayLikeKeys，否则调用baseKeys } /** * This method returns the first argument it receives. * * @static * @since 0.1.0 * @memberOf _ * @category Util * @param {*} value Any value. * @returns {*} Returns `value`. * @example * * var object = { 'a': 1 }; * * console.log(_.identity(object) === object); * // => true */ //返回接收到的第一个参数 function identity(value) { return value; } /** * Creates a function that returns the value at `path` of a given object. * * @static * @memberOf _ * @since 2.4.0 * @category Util * @param {Array|string} path The path of the property to get. * @returns {Function} Returns the new accessor function. * @example * * var objects = [ * { 'a': { 'b': 2 } }, * { 'a': { 'b': 1 } } * ]; * * _.map(objects, _.property('a.b')); * // => [2, 1] * * _.map(_.sortBy(objects, _.property(['a', 'b'])), 'a.b'); * // => [1, 2] */ function property(path) { return isKey(path) ? baseProperty(toKey(path)) : basePropertyDeep(path); } module.exports = orderBy;
