58个面向 Web 开发人员的JavaScript技巧汇总
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。
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 rating
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"); // true
params.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(2, 10); // 5
布尔技能
15、短路运算符
const a = d && 1;
const b = d || 1;
const c = !d;
16、确定数据类型 可确定数据类型：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"); // true
DataType({}, "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;
const flagB = false;
(flagA || flagB) && Func();
(flagA || !flagB) && Func();
flagA && flagB && Func();
flagA && !flagB && Func();
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 = [1,1,2,3,3,4,5,5]
const arr1 = [...new Set(arr)] //arr1 => [1,2,3,4,5]
25、混淆数组
function upsetArray(arr) {
return arr.slice().sort(() => Math.random() - 0.5)
}
const arr = [1,3,5,7,9,11]
const arr1 = upsetArray(arr)
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、false、‘’、0、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、在数组末尾插入成员
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key
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、创建指定长度数组
const arr = [...new Array(3).keys()];// arr => [0, 1, 2]
38、创建一个指定长度和等值的数组
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
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
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 with
function 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"));
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