字符串、数组、对象的转换

数组<==>字符串

1.数组转换成字符串 Array.prototype.join(‘分隔符’)

var arr=[1,'w','er']
console.log(arr.join())     // 1,w,er
console.log(arr.join('.'))  //1.w.er
console.log(arr.join(''))   //1wer

2.字符串转换成数组 String.prototype.split(‘按什么切割的切割符’)

var str='name=lx&age=21&sex=男'
console.log(str.split('&'))     // ["name=lx", "age=12", "sex=男"]
console.log(str.split('='))     // ["name", "lxl&age", "12&sex", "男"]

对象<==>字符串

1.对象转成字符串 JSON.stringify()

var obj={a:1,b:12,}
JSON.stringify(obj) // "{"a":1,"b":12}"

2.字符串转换成对象

var str='{"a":1,"b":12}'
JSON.parse(str)  // {a: 1, b: 12}

对象<==>数组

1.数组转换成对象

var list = {};
var arr = ["123","456","789"];
for (var key in arr) {
    list[key] = arr[key];
}
console.log(list);//{0: "123"，1: "456"，2: "789"}

2.对象转换成数组

      let list = Array.from(object)
      let list = Array.prototype.slice.call(object)
      let list = [...object]