beary

``` javascript function myajax(url, method) { return new Promise((resolve, reject) => { const xhr = new XMLHttpRequest(); xhr.open(method, url); xhr.send(null); xhr.onreadystatechange = function() { if (xhr.readyState == 4) { if...

``` javascript const arrs = [ { name: "可乐", categories: ["热门", "饮料"], }, { name: "苹果", categories: ["热门", "食物"], }, { name: "洗衣液", categories: ["生活用品"], }, ]; let map =...

``` javascript Array.prototype.map = function (callback) { const res = []; for (let i = 0; i < this.length; i++) { res.push(callback(this[i], i, this)); } return res; }; ```

``` javascript const arr = [1, 3, 55, 77, 1000]; // 1. 调用Math let res = Math.max(...arr); // 2. 排序 arr.sort((a, b) => a - b)[arr.length - 1]; // 3....

``` javascript function showTime(){ return new Promise((resolve, reject)=>{ setTimeout(()=>{ console.log(new Date()); resolve(); }, 3000); }) } const time = async () => { await showTime(); time(); } time(); ```

``` javascript function isValid(str, judge) { let j = 0; for (let i = 0; i < str.length; i++) { if (str[i] === judge[j] && j < judge.length) j++; }...

``` javascript const images = document.querySelectorAll("image"); const observer = new IntersectionObserver((entries, observer) => { entries.forEach((entry) => { if (entry.isIntersecting) { entry.target.src = entry.target.dataset.src; observer.unobserve(entry.target); } }); }); images.forEach((image) => {...

补充：react可以直接用组件

``` javascript const res = []; function getSymNum() { for (let i = 1; i

``` javascript function myNew(){ let obj = {}; let con = [].shift.call(arguments); obj.__proto__ = con.prototype; let res = con.call(obj, ...arguments); return res instanceof Obejct ? res : obj; } ```