js操作数组，对象转换

ES6方法 数组转对象

1、利用fromEntries()和map()函数，语法“Object.fromEntries(arr.map(item => [item.key, item]))”语句；

const arr = [
  { code: "1001", city: "北京" },
  { code: "1002", city: "深圳" },
];
const obj = Object.fromEntries(arr.map(item => [item.code, item.city]));

console.log(obj);

2、利用扩展运算符“...”，语法“{...arr}”。

const arr = [
  { key: "id", name: "编号" },
  { key: "name", name: "名称" },
];

const obj = {...arr} ;

console.log(obj);

3、使用for in 遍历

for(let key in arr) { //这里key索引
      obj[key] = arr[key]
    }

ES6方法 对象转数组

1、Array.from

let obj2 = {
    0:'zhangsan',
    1:'lisi',
    2:'wangwu',
    length:3
}
let arr2 = Array.from(obj2)
console.log(arr2);   //[ 'zhangsan', 'lisi', 'wangwu' ]

2、Array.prototype.slice.call

const arr = Array.prototype.slice.call(arrLike)