js對數組和對象之間的操作

數組和對象之間的操作，很多都依賴於map的方法

         map,是將數據進行遍歷，將返回值重新組成一個數組

1.將數組重新組成新數組對象

原理：利用數組的方法 map,對數組遍歷重構數組

       let arr = [
            {id:1,name:'a',age:15,fav:"籃球"},
            {id:2,name:'b',age:15,fav:"足球"},
            {id:3,name:'c',age:15,fav:"乒乓球"},
            {id:4,name:'d',age:15,fav:"排球"},
            {id:5,name:'e',age:15,fav:"羽毛球"}
        ];
        let arr1 = arr.map((item,index) => {
            return {peple:item.name,myFav:item.fav}
        });

打印的arr1 - 

 

 

2.給數組的每個對象添加一個屬性

原理 1- 利用map進行重構

       let arr = [
            {name:'a',age:15,fav:"籃球"},
            {name:'b',age:15,fav:"足球"},
            {name:'c',age:15,fav:"乒乓球"},
            {name:'d',age:15,fav:"排球"},
            {name:'e',age:15,fav:"羽毛球"}
        ];
        let arr1 = arr.map((item,index) => {
            return {peple:item.name,myFav:item.fav,index:index+1}
        });

原理2 - 利用深拷貝 + map

       let arr = [
            {name:'a',age:15,fav:"籃球"},
            {name:'b',age:15,fav:"足球"},
            {name:'c',age:15,fav:"乒乓球"},
            {name:'d',age:15,fav:"排球"},
            {name:'e',age:15,fav:"羽毛球"}
        ];
        let arr1 = arr.map((item,index) => {
            return Object.assign(item,{index:index+1})
        });

打印arr1

 

3.多個數組對象利用index進行對應

原理-利用解構+map

       let arr = [
            {name:'a',age:15,fav:"籃球"},
            {name:'b',age:15,fav:"足球"},
            {name:'c',age:15,fav:"乒乓球"},
            {name:'d',age:15,fav:"排球"},
            {name:'e',age:15,fav:"羽毛球"}
        ];

        let arr1 = [
            {key:'1',val:'sss'},
            {key:'2',val:'fsd'},
            {key:'3',val:'fds'},
            {key:'4',val:'fewf'},
            {key:'5',val:'ewd'}
        ]
        let arr2 = arr.map((item,index) => {
            return {...arr1[index],...item}
        });

打印arr2