JSON 隐藏的特殊用法

demo 1

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var  obj={id:1,name:'vingo'};console.log(JSON.stringify(obj));//   "{"id":1,"name":"vingo"}"

demo 2

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var  obj2={id:1,name:'vingo'};console.log(JSON.stringify(obj2),["id"]);//   "{"id":1}"

demo 3

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var  obj3={id:1,name:'vingo'};function f(key,value){    if(key==="id"){            return value*2;    }}console.log(JSON.stringify(obj),f);//   "{"id":2}"

demo 4

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var obj4={id:1,name:"vingo",toJSON:function(){ return {name:this.name} }}; console.log(JSON.stringify(obj4),f);//   "{"name":"vingo"}"

from : http://javascript.ruanyifeng.com/stdlib/json.html