1、json.stringify和json.parse用处

JSON.stringify() 将对象a转化成字符串s;
JSON.parse() 将字符串s转化成对象a
this.emptyForm = JSON.parse(JSON.stringify(this.form))

let arr = [1,2,3];

JSON.stringify(arr);//'[1,2,3]'

typeof JSON.stringify(arr);//string
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let string = '[1,2,3]';

console.log(JSON.parse(string))//[1,2,3]

console.log(typeof JSON.parse(string))//object
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//判断数组是否包含某对象
let data = [

  {name:'掘金'},

  {name:'css学习'},

  {name:'js学习'},

  ],

  val = {name:'掘金'};

JSON.stringify(data).indexOf(JSON.stringify(val)) !== -1; // true