数据类型的拷贝

//浅拷贝
var a={a:18};
var b=a;
b.m=22
console.log(a) {a: 18, m: 22}
console.log(b) {a: 18, m: 22}
 

//深拷贝
var c=JSON.stringify(a)
console.log(c) // {"a":18,"m":22}
Object.prototype.toString.call(c)
"[object String]"

var d=JSON.parse(c)
Object.prototype.toString.call(d)
"[object Object]"
d.e=88

console.log(a)
 {a: 18, m: 22}

console.log(d)
 {a: 18, m: 22, e: 88}