js简写整理
0.给身份证加* 号
let idNo = '5123456789789789789' //身份证号码 let manySpace=function(num,space){ //生成指定字符和个数的字符串 let str = '' for(let i=0;i<num;i++){ str+=space } return str } console.log(idNo.replace(/(\w{6})\w*(\w{4})/, `$1${manySpace(idNo.length-10,'*')}$2`)); // 结果51234********9789
1.通过条件判断给变量赋值布尔值的正确姿势
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// bad if (a === 'a') { b = true } else { b = false } // good b = a === 'a'
2.在if中判断数组长度不为零的正确姿势
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// bad if (arr.length !== 0) { // todo } // good if (arr.length) { // todo }
3.同理,在if中判断数组长度为零的正确姿势
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// bad if (arr.length === 0) { // todo } // good if (!arr.length) { // todo }
4.简单的if判断使用三元表达式
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// bad if (a === 'a') { b = a } else { b = c } // good b = a === 'a' ? a : c
5.使用includes简化if判断
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// bad if (a === 1 || a === 2 || a === 3 || a === 4) { // todo } // good let arr = [1, 2, 3, 4] if (arr.includes(a)) { // todo }
6.使用some方法判断是否有满足条件的元素
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// bad for (let i = 0; i < arr.length; i ++) { // todo arr[i].key = balabala } // good arr.forEach(item => { // todo item.key = balabala })
7.使用forEach方法遍历数组,不形成新数组
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// bad for (let i = 0; i < arr.length; i ++) { // todo arr[i].key = balabala } // good arr.forEach(item => { // todo item.key = balabala })
8.使用filter方法过滤原数组,形成新数组
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// bad let arr = [1, 3, 5, 7], newArr = [] for (let i = 0; i < arr.length; i ++) { if (arr[i] > 4) { newArr.push(arr[i]) } } // good let arr = [1, 3, 5, 7] let newArr = arr.filter(n => n > 4) // [5, 7]
9.使用map对数组中所有元素批量处理,形成新数组
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// bad let arr = [1, 3, 5, 7], newArr = [] for (let i = 0; i < arr.length; i ++) { newArr.push(arr[i] + 1) } // good let arr = [1, 3, 5, 7] let newArr = arr.map(n => n + 1) // [2, 4, 6, 8]
10.使用Object.values快速获取对象键值
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let obj = { a: 1, b: 2 } // bad let values = [] for (key in obj) { values.push(obj[key]) } // good let values = Object.values(obj) // [1, 2]
11.使用Object.keys快速获取对象键名
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let obj = { a: 1, b: 2 } // bad let keys = [] for (value in obj) { keys.push(value) } // good let keys = Object.keys(obj) // ['a', 'b']
12.解构数组进行变量值的替换
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// bad let a = 1, b = 2 let temp = a a = b b = temp // good let a = 1, b = 2 [b, a] = [a, b]
13.解构对象
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// bad setForm (person) { this.name = person.name this.age = person.age } // good setForm ({name, age}) { this.name = name this.age = age }
14.解构时重命名简化命名
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// bad setForm (data) { this.one = data.aaa_bbb_ccc_ddd this.two = data.eee_fff_ggg } // good setForm ({aaa_bbb_ccc_ddd, eee_fff_ggg}) { this.one = aaa_bbb_ccc_ddd this.two = eee_fff_ggg } // best setForm ({aaa_bbb_ccc_ddd: one, eee_fff_ggg: two}) { this.one = one this.two = two }
15.解构时设置默认值
// bad setForm ({name, age}) { if (!age) age = 16 this.name = name this.age = age } // good setForm ({name, age = 16}) { this.name = name this.age = age }
16.||短路符设置默认值
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let person = { name: '张三', age: 38 } let name = person.name || '佚名'
17.&&短路符判断依赖的键是否存在防止报错'xxx of undfined'
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let person = { name: '张三', age: 38, children: { name: '张小三' } } let childrenName = person.children && person.childre.name
18.字符串拼接使用${}
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let person = { name: 'LiMing', age: 18 } // bad function sayHi (obj) { console.log('大家好,我叫' + person.name = ',我今年' + person.age + '了') } // good function sayHi (person) { console.log(`大家好,我叫${person.name},我今年${person.age}了`) } // best function sayHi ({name, age}) { console.log(`大家好,我叫${name},我今年${age}了`) }
19.函数使用箭头函数
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let arr [18, 19, 20, 21, 22] // bad function findStudentByAge (arr, age) { return arr.filter(function (num) { return num === age }) } // good let findStudentByAge = (arr, age)=> arr.filter(num => num === age)
20.函数参数校验
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// bad let findStudentByAge = (arr, age) => { if (!age) throw new Error('参数不能为空') return arr.filter(num => num === age) } // good let checkoutType = () => { throw new Error('参数不能为空') } let findStudentByAge = (arr, age = checkoutType()) => arr.filter(num => num === age)
转载来自https://juejin.cn/post/6903325147420164104