JS 把数组对象转化为对象

 一、
     let arrObj = [
        {
          0: 'a',
          1: 'b',
          2: 'c',
        },
      ]
      console.log(arrObj)
      arrObj.forEach((item) => {
        console.dir(item)
      })
二、

const lessons = [
  {
    title: "媒体查询响应式布局",
    category: "css"
  },
  {
    title: "FLEX 弹性盒模型",
    category: "css"
  },
  {
    title: "MYSQL多表查询随意操作",
    category: "mysql"
  }
];
let lessonObj = lessons.reduce((obj, cur, index) => {
  obj[`${cur["category"]}-${index}`] = cur;
  return obj;
}, {});
console.log(lessonObj); //{css-0: {…}, css-1: {…}, mysql-2: {…}}
console.log(lessonObj["css-0"]); //{title: "媒体查询响应式布局", category: "css"}
三、

const array = [{ book: 5, car: 6, pc: 7 }, { headphone: 9, keyboard: 10 }],
object = Object.assign({}, ...array);