- 扁平化嵌套数组/flat实现描述：将嵌套多层的数组展开平铺成只有一层的数组。let array = [1, [1, 2, 3], [1, [2, {}]] ]handle(array) // [1, 1, 2, 3, 1, 2, {}]方法一：const handle = array => JSON.parse(
[${JSON.stringify(arr).replace(/\[|]/g,'')}])handle(array) // [ 1, 1, 2, 3, 1, 2, {} ]知识点：JSON.parse()/JSON.stringify()、String.prototype.replace()方法二：const handle = array => array.reduce((accumulator, currentValue) => accumulator.concat(Array.isArray(currentValue) ? hanlde(currentValue), currentValue), [])handle(array) // [ 1, 1, 2, 3, 1, 2, {} ]知识点：Array.prototype.reduce()、Array.prototype.concat()方法三：const handle = array => { while(array.some(item => Array.isArray(item))) { array = [].concat(…array) } return array}handle(array) // [ 1, 1, 2, 3, 1, 2, {} ]知识点：while、Array.prototype.some()、展开语法(Spread syntax)其它方法：……2. 数组去重描述：将数组中重复的元素过滤掉。let array = [1, 2, 1, ‘3’, ‘3’, 0 , 1]handle(array) // [1, 2, ‘3’, 0]方法一：const handle = array => […new Set(array)]handle(array) // [ 1, 2, ‘3’, 0 ]知识点：Set方法二：const handle = array => array.reduce((accumulator, currentValue) => { !accumulator.includes(currentValue) && accumulator.push(currentValue) return accumulator}, [])handle(array) // [ 1, 2, ‘3’, 0 ]知识点：Array.prototype.includes()方法三：const handle = array => { let map = new Map() return array.filter(item => map.has(item) ? false : map.set(item))}handle(array) // [ 1, 2, ‘3’, 0 ]知识点：Map、Array.prototype.filter()其它方法：……3. 模拟bind实现Function.prototype.bind = function () { let self = this, args = Array.from(arguments), context = args.shift(); return function () { return self.apply(context, args.concat(…arguments)) };};知识点：apply、call、bind4. 模拟New实现const handle = function() { let fn = Array.prototype.shift.call(arguments) let obj = Object.create(fn.prototype) let o = fn.apply(obj, arguments) return typeof o === ‘object’ ? o : obj;}知识点：Object.create()5. 格式化数字const num = 123456789;const handle = num => String(num).replace(/\B(?=(\d{3})+(?!\d))/g, ‘,’)handle(num) // 123,456,789知识点：正则表达式、String.prototype.replace()6. 回文判断const num = 123456654321;const str = ‘abababababab’;const handle = params => { let str_1 = String(params).replace(/[^0-9A-Za-z]/g, ‘’).toLowerCase(); let str_2 = str_1.split(’’).reverse().join(); return str_1 === str_2 ? true : false}handle(num) // truehandle(str) // false知识点：String.prototype.split()、Array.prototype.join()7. 函数节流定时器const handle = (fn, interval) => { let timeId = null; return function() { if (!timeId) { timeId = setTimeout(() => { fn.apply(this, arguments) timeId = null }, interval) } }}知识点：window.setTimeout时间戳const handle = (fn, interval) => { let lastTime = 0 return function () { let now = Date.now(); if (now - lastTime > interval) { fn.apply(this, arguments) lastTime = now } }}8. 函数防抖const handle = (fn, delay) => { let timeId; return function() { if (timeId) clearTimeout(timeId) timeId = setTimeout(() => { fn.apply(this, arguments) }, delay) }}函数节流、函数防抖区别：函数节流和函数防抖较容易混淆，可以这么比喻，对于函数节流，门外有人频繁敲门，但是门卫按固定时间来决定是否开门。对于函数防抖，门外有人频繁敲门，门卫按最后一次敲门来决定是否开门。知识点：window.clearTimeout9. 发布订阅模式class Pubsub { constructor() { this.handles = {} } subscribe(type, handle) { if (!this.handles[type]) { this.handles[type] = [] } this.handles[type].push(handle) } unsubscribe(type, handle) { let pos = this.handles[type].indexOf(handle) if (!handle) { this.handles.length = 0 } else { ~pos && this.handles[type].splice(pos, 1) } } publish() { let type = Array.prototype.shift.call(arguments) this.handles[type].forEach(handle => { handle.apply(this, arguments) }) }}const pub = new Pubsub()pub.subscribe(‘a’, function() {console.log(‘a’, …arguments)})pub.publish(‘a’, 1, 2, 3)// a 1 2 3