js将数组转化为一个对象obj，将数组中的内容作为对象的key转化为对象，将数组中的某项内容作为分类来转成对象

1.js数组转成对象

var list = {};
var arr = ["123","456","789"];
// for in 循环
for (var key in arr) {
    list[key] = arr[key];
}
console.log(list); //控制台打印

打印如下

我的思路就是这样，不止这一种其他循环也可以forEach、map、reduce等等

2.将数组中的内容作为对象的key转化为对象

//数组
var formArr =  [
{name: "张三", num: "1"},
{name: "李四", num: "2"},
{name: "王二", num: "3"},
{name: "麻子", num: "4"}
];

//创建对象
var obj={ };

//map循环方式
  formArr.map(function (e, item) {
  obj[e.num] = e.name;
  });
console.log(obj); //控制台打印

结果打印：obj = {1: “张三”, 2: “李四”, 3: “王二”, 4: “麻子”}
不止这一种其他循环也可以forEach、for in、reduce等等

3.将数组中的某项内容作为分类来转成对象
例如页面上有个小组(group)成员，点击那个小组显示那个小组的成员

//数组
var formArr =  [
{name: "张三", group: "1"},
{name: "李四", group: "1"},
{name: "王二", group: "2"},
{name: "麻子", group: "2"},
{name: "小明", group: "3"},
{name: "小红", group: "3"},
{name: "隔壁", group: "4"},
{name: "老王", group: "4"}
];

//创建对象
let obj = {}

//forEach循环
formArr.forEach(item => {
    if (!obj[item.group]) {
      obj[item.group] = [item]
    } else {
      obj[item.group].push(item)
    }
  })
console.log(obj) //控制台打印

结果打印：

展开

然后在页面上循环展示即可