Array.prototype.filter()
1 <!DOCTYPE html> 2 <html> 3 4 <head> 5 <meta charset="UTF-8"> 6 <title></title> 7 </head> 8 9 <body> 10 <script type="text/javascript"> 11 var words = ['spray', 'limit', 'elite', 'exuberant', 'destruction', 'present']; 12 13 const result = words.filter(word => word.length > 6); 14 15 console.log(result); 16 17 function isBigEnough(value) { 18 if(value >= 10){ 19 return true;//=== return value >=10 20 } 21 } 22 23 var filtered = [12, 5, 8, 130, 44].filter(isBigEnough); 24 console.log(filtered) 25 26 27 28 29 30 31 32 var fruits = ['apple', 'banana', 'grapes', 'mango', 'orange']; 33 34 /** 35 * Array filters items based on search criteria (query) 36 */ 37 function filterItems(query) { 38 //基于搜索的字母来从数组中找类似的选项 39 return fruits.filter(function(el) { 40 return el.toLowerCase().indexOf(query.toLowerCase()) > -1; 41 }) 42 } 43 44 console.log(filterItems('ap')); // ['apple', 'grapes'] 45 console.log(filterItems('an')); // ['banana', 'mango', 'orange'] 46 47 48 const fruits1 = ['apple', 'banana', 'grapes', 'mango', 'orange']; 49 50 /** 51 * Array filters items based on search criteria (query) 52 */ 53 const filterItems1 = (query) => { 54 //箭头函数的写法 55 return fruits1.filter(el => el.toLowerCase().indexOf(query.toLowerCase()) > -1); 56 }; 57 58 console.log(filterItems1('ap')); // ['apple', 'grapes'] 59 console.log(filterItems1('an')); // ['banana', 'mango', 'orange'] 60 61 62 63 64 65 66 67 if (!Array.prototype.filter){ 68 Array.prototype.filter = function(func, thisArg) { 69 'use strict'; 70 if ( ! ((typeof func === 'Function' || typeof func === 'function') && this) ) 71 throw new TypeError(); 72 73 var len = this.length >>> 0,//因爲雖然這個 map 方法是在Array 的 prototype上的， 74 //但實際上調用的時候，this 不一定是 Array類型，length不能得到保證，加上位運算後，可以將不確定的値轉換成Number。 75 res = new Array(len), // preallocate array 76 t = this, c = 0, i = -1; 77 if (thisArg === undefined){ 78 while (++i !== len){ 79 // 检查是否设置了密钥 80 if (i in this){ 81 if (func(t[i], i, t)){ 82 res[c++] = t[i]; 83 } 84 } 85 } 86 } 87 else{ 88 while (++i !== len){ 89 // 检查是否设置了密钥 90 if (i in this){ 91 if (func.call(thisArg, t[i], i, t)){ 92 res[c++] = t[i]; 93 } 94 } 95 } 96 } 97 98 res.length = c; // 将数组缩小到适当的大小 99 return res; 100 }; 101 } 102 </script> 103 </body> 104 105 </html>
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/filter 资料来自MDN
