58个面向 Web 开发人员的JavaScript技巧汇总
web前端开发
共 8707字，需浏览 18分钟
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2022-04-18 19:16
来源 | https://blog.bitsrc.io/common-js-development-skills-5053f0a74ced
作为程序员，编写代码也需要大量的技巧。好的代码可以让人耳目一新、通俗易懂、舒适自然，同时又充满成就感。
因此，整理了一些近三年，我使用过的JavaScript开发技巧，希望能让大家写出耳目一新、通俗易懂、舒适自然的代码。
字符串技巧
1、比较时间
const time1 = "2022-03-02 09:00:00";const time2 = "2022-03-02 09:00:01";const overtime = time1 < time2;// overtime => true
2、格式化money
const ThousandNum = num => num.toString().replace(/\B(?=(\d{3})+(?!\d))/g, ",");const money = ThousandNum(1000000);// money => '1,000,000'
3、生成随机ID
const RandomId = len => Math.random().toString(36).substr(3, len);const id = RandomId(10);// id => "xdeguewg1f"
4、生成随机 HEX 颜色值
const RandomColor = () => "#" + Math.floor(Math.random() * 0xffffff).toString(16).padEnd(6, "0");const color = RandomColor();// color => "#2cbf89"
5、Generate star ratings
const StartScore = rate => "★★★★★☆☆☆☆☆".slice(5 - rate, 10 - rate);const start = StartScore(3);// start => '★★★☆☆'
6、网址查询参数
const params = new URLSearchParams(location.search.replace(/\?/ig, "")); // location.search = "?name=test&sex=man"params.has("test"); // trueparams.get("sex"); // "man"
数字技能
7、Arrangement
用 Math.floor() 代替正数，用 Math.ceil() 代替负数
const num1 = ~~ 1.19;const num2 = 2.29 | 0;const num3 = 3.09 >> 0;// num1 num2 num3 => 1 2 3
8、零填充
const FillZero = (num, len) => num.toString().padStart(len, "0");const num = FillZero(1234, 5);// num => "01234"
9、转数
仅对 null、“”、false、数字字符串有效
const num1 = +null;const num2 = +"";const num3 = +false;const num4 = +"169";// num1 num2 num3 num4 => 0 0 0 169
10、时间戳
const timestamp = +new Date("2022-03-22");// timestamp => 1647907200000
11、精确小数
const RoundNum = (num, decimal) => Math.round(num * 10 ** decimal) / 10 ** decimal;const num = RoundNum(1.2345, 2);// num => 1.23
12、平价
const OddEven = num => !!(num & 1) ? "odd" : "even";const num = OddEven(2);// num => "even"
13、取最小值最大值
const arr = [0, 1, 2, 3];const min = Math.min(...arr);const max = Math.max(...arr);// min max => 0 3
14、生成范围随机数
const RandomNum = (min, max) => Math.floor(Math.random() * (max - min + 1)) + min;const num = RandomNum(1, 10); // 5
布尔技能
15、短路运算符
const a = d && 1; // Fake operation, judge from left to right, return a false value when encountering a false value, and no longer execute it later, otherwise return the last true valueconst b = d || 1; // Take the true operation, judge from left to right, return the true value when encountering the true value, and do not execute it later, otherwise return the last false valueconst c = !d; // Returns false if a single expression converts to true, otherwise returns true
16、确定数据类型
可确定的类型：undefined、null、string、number、boolean、array、object、symbol、date、regexp、function、asyncfunction、arguments、set、map、weakset、weakmap
function DataType(tgt, type) {const dataType = Object.prototype.toString.call(tgt).replace(/\[object (\w+)\]/, "$1").toLowerCase();return type ? dataType === type : dataType;}DataType("test"); // "string"DataType(20220314); // "number"DataType(true); // "boolean"DataType([], "array"); // trueDataType({}, "array"); // false
17、检查数组是否为空
const arr = [];const flag = Array.isArray(arr) && !arr.length;// flag => true
18、满足条件时执行
const flagA = true; // Condition Aconst flagB = false; // Condition B(flagA || flagB) && Func(); // Execute when A or B is satisfied(flagA || !flagB) && Func(); // Execute when A is satisfied or B is not satisfiedflagA && flagB && Func(); // Execute when both A and B are satisfiedflagA && !flagB && Func(); // Execute when A is satisfied and B is not satisfied
19、如果非假则执行
const flag = false; // undefined、null、""、0、false、NaN!flag && Func();
20、数组不为空时执行
const arr = [0, 1, 2];arr.length && Func();
21、对象不为空时执行
const obj = { a: 0, b: 1, c: 2 };Object.keys(obj).length && Func();
阵列技能
22、克隆数组
const _arr = [0, 1, 2];const arr = [..._arr];// arr => [0, 1, 2]
23、合并数组
const arr1 = [0, 1, 2];const arr2 = [3, 4, 5];const arr = [...arr1, ...arr2];// arr => [0, 1, 2, 3, 4, 5];
24、去重数组
const arr = [...new Set([0, 1, 1, null, null])];// arr => [0, 1, null]
25、混淆数组
const arr = [0, 1, 2, 3, 4, 5].slice().sort(() => Math.random() - .5);// arr => [3, 4, 0, 5, 1, 2]
26、清空数组
const arr = [0, 1, 2];arr.length = 0;// arr => []
27、截断数组
const arr = [0, 1, 2];arr.length = 2;// arr => [0, 1]
28、交换数值
let a = 0;let b = 1;[a, b] = [b, a];// a b => 1 0
29、过滤空值
空值：undefined,null,””,0,false,NaN
const arr = [undefined, null, "", 0, false, NaN, 1, 2].filter(Boolean);// arr => [1, 2]
30、在数组开头插入成员
let arr = [1, 2];arr.unshift(0);arr = [0].concat(arr);arr = [0, ...arr];// arr => [0, 1, 2]
31、在数组末尾插入元素
let arr = [0, 1];arr.push(2);arr.concat(2);arr[arr.length] = 2;arr = [...arr, 2];// arr => [0, 1, 2]
32、计算数组成员的数量
const arr = [0, 1, 1, 2, 2, 2];const count = arr.reduce((t, v) => {t[v] = t[v] ? ++t[v] : 1;return t;}, {});// count => { 0: 1, 1: 2, 2: 3 }
33、解构嵌套数组成员
const arr = [0, 1, [2, 3, [4, 5]]];const [a, b, [c, d, [e, f]]] = arr;// a b c d e f => 0 1 2 3 4 5
34、解构数组成员别名
const arr = [0, 1, 2];const { 0: a, 1: b, 2: c } = arr;// a b c => 0 1 2
35、解构数组成员默认值
const arr = [0, 1, 2];const [a, b, c = 3, d = 4] = arr;// a b c d => 0 1 2 4
36、获取随机数组成员
const arr = [0, 1, 2, 3, 4, 5];const randomItem = arr[Math.floor(Math.random() * arr.length)];// randomItem => 1
37、创建指定长度的数组
const arr = [...new Array(3).keys()];// arr => [0, 1, 2]
38、创建一个指定长度和相等值的数组
const arr = new Array(3).fill(0);// arr => [0, 0, 0]
对象技能
39、克隆对象
const _obj = { a: 0, b: 1, c: 2 };const obj = { ..._obj };const obj = JSON.parse(JSON.stringify(_obj));// obj => { a: 0, b: 1, c: 2 }
40、合并对象
const obj1 = { a: 0, b: 1, c: 2 };const obj2 = { c: 3, d: 4, e: 5 };const obj = { ...obj1, ...obj2 };// obj => { a: 0, b: 1, c: 3, d: 4, e: 5 }
41、对象变量属性
const flag = false;const obj = {a: 0,b: 1,[flag ? "c" : "d"]: 2};// obj => { a: 0, b: 1, d: 2 }
42、创建一个纯空对象
const obj = Object.create(null);Object.prototype.a = 0;// obj => {}
43、删除对象无用属性
const obj = { a: 0, b: 1, c: 2 };const { a, ...rest } = obj;// rest => { b: 1, c: 2 }
44、解构对象属性嵌套
const obj = { a: 0, b: 1, c: { d: 2, e: 3 } };const { c: { d, e } } = obj;// d e => 2 3
45、解构对象属性别名
const obj = { a: 0, b: 1, c: 2 };const { a, b: d, c: e } = obj;// a d e => 0 1 2
46、解构对象属性默认值
const obj = { a: 0, b: 1, c: 2 };const { a, b = 2, d = 3 } = obj;// a b d => 0 1 3
函数技能
47、函数自执行
const Func = function() {}(); // Commonly used(function() {})(); // Commonly used(function() {}()); // Commonly used[function() {}()];+ function() {}();- function() {}();~ function() {}();! function() {}();new function() {};new function() {}();void function() {}();typeof function() {}();delete function() {}();1, function() {}();1 ^ function() {}();1 > function() {}();
48、一次性函数
适合运行一些只需要执行一次的初始化代码。
function Func() {console.log("x");Func = function() {console.log("y");}}
49、延迟加载函数
当函数中的复杂判断分支越来越多时，可以大大节省资源开销。
function Func() {if (a === b) {console.log("x");} else {console.log("y");}}// replace withfunction Func() {if (a === b) {Func = function() {console.log("x");}} else {Func = function() {console.log("y");}}return Func();}
50、检测非空参数
function IsRequired() {throw new Error("param is required");}function Func(name = IsRequired()) {console.log("I Love " + name);}Func(); // "param is required"Func("You"); // "I Love You"
51、字符串创建函数
const Func = new Function("name", "console.log(\"I Love \" + name)");52、优雅地处理错误信息
try {Func();} catch (e) {location.href = "https://stackoverflow.com/search?q=[js]+" + e.message;}
53、优雅地处理 Async/Await 参数
function AsyncTo(promise) {return promise.then(data => [null, data]).catch(err => [err]);}const [err, res] = await AsyncTo(Func());
54、优雅地处理多个函数返回值
function Func() {return Promise.all([fetch("/user"),fetch("/comment")]);}const [user, comment] = await Func();
DOM 技能
55、显示所有 DOM 边框
[].forEach.call($$("*"), dom => {dom.style.outline = "1px solid #" + (~~(Math.random() * (1 << 24))).toString(16);});
56、响应式页面
页面基于设计图但需要适配多个模型，元素大小使用rem设置。
function AutoResponse(width = 750) {const target = document.documentElement;target.clientWidth >= 600? (target.style.fontSize = "80px"): (target.style.fontSize = target.clientWidth / width * 100 + "px");}
57、过滤 XSS
function FilterXss(content) {let elem = document.createElement("div");elem.innerText = content;const result = elem.innerHTML;elem = null;return result;}
58、访问本地存储
const love = JSON.parse(localStorage.getItem("love"));localStorage.setItem("love", JSON.stringify("I Love You"));
总结
以上就是我整理汇总的58个JavaScript的小技巧，希望对你有所帮助。
感谢您的阅读，祝编程愉快！
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