深浅拷贝

目的：将 cloneFather 拷贝给 cloneSon

let cloneFather = { item1: '1', item2: '2', arr: ['3'] }
let cloneSon = {}

浅拷贝

function extentCopy(obj) {
    let o = {}
    for (let i in obj) {
        o[i] = obj[i]
    }
    o.uper = obj
    return o
}
// cloneSon = extentCopy(cloneFather)
// cloneSon.arr.push('0')
// 问题：如果父对象的属性等于数组或另一个对象，那么子克隆改变，父对象跟着改变
// 如下 father 的 arr 变为 ['3', '0']
console.log(cloneSon, cloneFather);

深拷贝

可以解决浅拷贝的问题

function deepCopy(obj, item) {
    let o = item || {}
    for (let i in obj) {
        if (typeof obj[i] === 'object') {
            o[i] = (obj[i].constructor === Array) ? [] : {}
            deepCopy(obj[i], o[i])
        } else {
            o[i] = obj[i]
        }
    }
    return o
}

cloneSon = deepCopy(cloneFather)
cloneSon.arr.push('0')
console.log(cloneSon, cloneFather);