递归实现深拷贝

hashMap部分解决对象循环引用问题

var obj = { name: 'Jack', test: function () { console.log('obj'); }, zero: 0, hobby: [null, undefined, 0, 'haha'] } function copy (source, hashMap = new WeakMap()) { //判断是否已经拷贝过 if (hashMap.get(source)) return hashMap.get(source) /* 实现方式一 // 获取source数据类型 const type1 = ((Object.prototype.toString.call(source)).split(' ')[1]).slice(0,-1) let target; switch (type1) { case 'Object': target = {} break; case 'Array': target = [] break; } */ //实现方式二 let target = new source.constructor() hashMap.set(source, target) for (const key in source) { if (Object.prototype.hasOwnProperty.call(source, key)) { const element = source[key]; const type = ((Object.prototype.toString.call(element)).split(' ')[1]).slice(0,-1) if (type == 'Object') { target[key] = copy(element,hashMap) } else if (type == 'Array') { target[key] = copy(element,hashMap) } else target[key] = element } } return target } let o =copy(obj) //循环引用 let test1 = {},test2 = {}; test1.test2 = test2 test2.test1 = test1 console.log(copy(test2));