for循环遍历json(附习题及答案)

三种方法

var mapColumn = {  
             "vdoing" : "访问深度",  
             "_visitorNumber": "访问量",  
             "_pageViews": "浏览量",  
             "_jumpOutRate": "跳出率",  
             "_avgAccessTime": "平均访问时长",  
             "_allTargetConvRate": "转化率",  
             "_orderTotalPrice": "总收益"  
          
         }; 

一、原生

var target=[];  
var targetl=[];
for (var key in mapColumn) {  
     target.push(key);  
     targetl.push(mapColumn[key]);
}  
console.log(target); 
console.log(targetl);

二、Jquery

var m_list = [];
var m_lists = [];
var m_listall = [];
$.each(mapColumn,function(key,value){
    m_list.push(key);      //获取所有的key
    m_lists.push(value);   //获取所有的value
    m_listall.push({       //获取拼接
        title:key,
        name:value
    })
})
console.log(m_list); 
console.log(m_lists);
console.log(m_listall);

三、ES6字符串拼接

<div class="part1"></div>

var data = [{ 
             "vdoing" : "访问深度",  
             "_visitorNumber": "访问量",  
             "_pageViews": "浏览量",  
             "_jumpOutRate": "跳出率"  
          
        },{ 
             "vdoing" : "访问深度1",  
             "_visitorNumber": "访问量1",  
             "_pageViews": "浏览量1",  
             "_jumpOutRate": "跳出率1"            
        }]; 

for (var i = 0; i < data.length; i++) {
     /*es6模板字符串*/
     $(".part1").append(`<div>
         <span title="${data[i].vdoing}">${data[i].vdoing}</span>
         <span title="${data[i]._visitorNumber}">${data[i]._visitorNumber}</span>
         <span title="${data[i]._pageViews}">${data[i]._pageViews}</span>
         <span title="${data[i]._jumpOutRate}">${data[i]._jumpOutRate}</span>
     </div>`);
}

---

从别的地方看到的不错的习题，实际工作中也常用到

一、从某数据库接口得到如下值：

{
 rows: [
  ["Lisa", 16, "Female", "2000-12-01"],
  ["Bob", 22, "Male", "1996-01-21"]
 ],
 metaData: [
  {name: "name", note: ''},
  {name: "age", note: ''},
  {name: "gender", note: ''},
  {name: "birthday", note: ''}
 ]
}

rows是数据，metaData是对数据的说明。现写一个函数，将上面的Object转化为期望的数组：

[
 {name: "Lisa", age: 16, gender: "Female", birthday: "2000-12-01"},
 {name: "Bob", age: 22, gender: "Male", birthday: "1996-01-21"},
]

答案：两种，for循环和reduce

var temparry = [];
var result = [];
for (var k = 0; k < data.metaData.length; k++) {
    var a = data.metaData[k].name;
    temparry.push(a);
}
for (var i = 0; i < data.rows.length; i++) {
    var ob = {};
    for (var j = 0; j < temparry.length; j++) {

        var name = temparry[j];
        ob[name] = data.rows[i][j];
    }
    result.push(ob);

}
console.log(result);

var result = data.rows.reduce(function(prev1, cur1) {
    console.log('prev1:' + prev1);
    console.log('cur1:' + cur1);
    prev1.push(data.metaData.reduce(function(prev, cur, index) {
        prev[cur.name] = cur1[index];
        return prev;
    }, {}))
    return prev1;
}, []);

//console.log(result);
//console.log(result[0]);
//console.log(result[1]);

二、数组

a = [
{id: 10001, name: "Lisa", age: 16},
{id: 10002, name: "Bob", age: 22},
{id: 10003, name: "Alice", age: 20},
];

数组

b = [
{id: 10001, gender: "Female"},
{id: 10002, name: "Bob King", birthday: "1996-01-22"},
{id: 10005, name: "Tom", birthday: "2000-01-01"},
];

写一个函数按id用b更新a,期望得到的结果为：

[
{id: 10001, name: "Lisa", age: 16, gender: "Female"},
{id: 10002, name: "Bob King", birthday: "1996-01-22", age: 22},
{id: 10003, name: "Alice", age: 20},
{id: 10005, name: "Tom", birthday: "2000-01-01"},
]

这个自己写吧，不附答案了