Pgy121的博客

字符串let str = 'www.baidu.com'let n1 = str.includes('yyy')let n2 = str.startsWith('baidu', 4) // 从0开始数let n3 = str.endsWith('baidu', 9) // 从1开始数console.log(n1) // falseconsole.log(n2) // trueconsole.log(n3) //true模板字符串let userName = 'xiaomin'let u

let add = (...c) => { let sum = 0; for (const item of c) { sum += item } return sum}let sum = [2, 3, 3, 4, 6, 6, 6, 888]let n = add(...sum)console.log(n); // 918

map可以是 任意数据类型let num = 123;let arr = [1, 2, 3, 4];let fun = function () { };let obj = {};const map1 = new Map();map1.set(num, "q1");map1.set(arr, "q2");map1.set(fun, "q3");map1.set(obj, "q4");map1.set('aaa', "q5");for (const key of map1.keys())

const list = document.getElementById('list')// 创建一个文档片段，此时还没有插入到DOM接口中const frag = document.createDocumentFragment()for (let i = 0; i < 10; i++) { const li = document.createElement('li') li.innerHTML = `LIST ITEM ${i}` li.addEventListener('click',

function ajax (url) { const p = new Promise((resolve, reject) => { const xhr = new XMLHttpRequest() xhr.open('get', url, true) xhr.onreadystatechange = function () { if (xhr.readyState === 4) { if (xhr.status === 200) { resolve(JSON.p