数组、对象数组转化成JSON对象的情况

1、数组转化成JSON对象后，key值是索引，value是数组对应的值。

    //数组也可以转化成JSON对象    var jStr3 = "[[10,20,30],40,50,60]";    var j3 = JSON.parse(jStr3);    for(let key in j3){        console.log('key:',key);    }//    key: 0//    key: 1//    key: 2//    key: 3    for(let value of j3){        console.log('value:',value);    }//    value: (3) [10, 20, 30]//    value: 40//    value: 50//    value: 60    j3.forEach((item,index)=>{        console.log('item:',item,'index:',index);    })//    item: (3) [10, 20, 30] index: 0//    item: 40 index: 1//    item: 50 index: 2//    item: 60 index: 3    j3 = JSON.parse(jStr3,(key,value)=>{        console.log('key:',key,'value:',value);    });// 把所有值都遍历出来了//    key: 0 value: 10//    key: 1 value: 20//    key: 2 value: 30//    key: 0 value: (3) [empty × 3]//    key: 1 value: 40//    key: 2 value: 50//    key: 3 value: 60//    key:  value: (4) [empty × 4]

2、数组对象可以直接序列化成字符串

var jStr31 = [[10,20,30],40,50,60];    console.log(JSON.stringify(jStr31));    console.log(jStr31.toString());    console.log(jStr31.join('-'));//    [[10,20,30],40,50,60]//    10,20,30,40,50,60//    10,20,30-40-50-60

3、对象数组转化成JSON对象

var jStr = '[{"name":"a"},{"name":"b"}]';var j = JSON.parse(jStr);console.log(j);//    (2) [{…}, {…}]//    0: {name: "a"}//    1: {name: "b"}//    length: 2//    __proto__: Array(0)for(let key in j){   console.log('key:',key)}//    key: 0//    key: 1for(let item of j){    console.log('item of:',item.name);}//    item of: {name: "a"}//    item of: {name: "b"}j.forEach((item,index)=>{     console.log('index:',index,'item:',item);    })//    index: 0 item: {name: "a"}//    index: 1 item: {name: "b"}