区分

B复制了A的值，如果A被修改，B的值也被改变，那就是浅拷贝。

如果B的值没有跟着修改，那就是深拷贝

深浅拷贝的方式

1、遍历赋值

2、Object.create()

3、JSON.parse()和JSON.stringify()

浅拷贝-遍历

    let a = {name:"jack",obj:{str:"ccc",arr:[1,2,3]},arr:[4,5,6]}let b = {};for(let i in a){b[i] = a[i];}
​// console.log(a);a.arr[1] = "aaa";console.log(b);

深拷贝-递归

   let a = {name:"jack",obj:{str:"ccc",arr:[1,2,3]},arr:[4,5,6]}
​function deepclone(startobj,endobj){let obj = endobj || {};for(let i in startobj){if(typeof startobj[i] === "object"){obj[i] = startobj[i].constractor === Array ? [] : {};deepclone(startobj[i],obj[i]);}else{obj[i] = startobj[i];}}return obj;}
​let b = deepclone(a);console.log(a);console.log(b);a.obj.str = "nerwwww";console.log(a);console.log(b);

深拷贝-JSON.parse、JSON.stringfy

    let a = {name:"jack",obj:{str:"ccc",arr:[1,2,3]},arr:[4,5,6]}
​let b = JSON.parse(JSON.stringify(a));
​console.log(a);console.log(b);a.obj.str = "nerwwww";console.log(a);console.log(b);