foreach、for、for in循环方式

最新推荐文章于 2023-03-14 11:09:58 发布

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最新推荐文章于 2023-03-14 11:09:58 发布

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原文链接：http://www.cnblogs.com/yixiaoyang-/p/9989831.html

本文通过具体示例，介绍了如何使用JavaScript遍历数组和对象，包括使用forEach进行数组遍历，for...in进行对象遍历，以及传统for循环的使用。同时，展示了如何在遍历过程中修改数组中对象的属性。

$(function(){
    var data1 =
        [
            {
                id:'126652',
                no: '1',
                longitude: '103.94292',
                latitude: '30.620123',
                distance:'253'
            }, {
                id:'122855',
                no: '2',
                longitude: '103.94292',
                latitude: '30.620123',
                distance:'258.25'
            }, {
                id:'1285569',
                no: '3',
                longitude: '103.94292',
                latitude: '30.620123',
                distance:'253'
            }, {
                id:'1222555',
                no: '4',
                longitude: '103.94292',
                latitude: '30.620123',
                distance:'253'
            }]

    //遍历数组而设计
    data1.forEach(function (val,index,arr) {
          console.log(val) //{id: "126652", no: "1", longitude: "103.94292", latitude: "30.620123", distance: "253"}
          console.log(val.no);//1 2 3 4
          console.log(index);//0 1 2 3
          console.log(arr);//整个数组
    })
    var data2 = {a:'1',b:'2',c:'3',d:'4'}
    //循环对象而设计
    for(let i in data2){
        console.log(i)//a b c d
        console.log(data2[i])//1 2 3 4
    }
    var data3 = [1,2,3,4]
    //最原始遍历方式
    for(var i=0;i<data3.length;i++){
        console.log(data3[i])//1 2 3 4
    }
})




//修改某一条对象数据值

var stooges = [
 2   {label: 1, value: 1, placeCode: 'sh', stock_code: 40},
 3   {label: 1, value: 1, placeCode: 'sh', stock_code: 50},
 4   {label: 1, value: 1, placeCode: 'sz', stock_code: 60, status: 1},
 5   {label: 1, value: 1, placeCode: 'sz', stock_code: 39, status: 1}
 6 ];
 7 
 8 for (var i = 0; i < stooges.length; i++) {
 9   var item = stooges[i];
10   if (item.placeCode == "sh") {
11     item.placeCode = "沪";
12   }
13   if (item.placeCode == "sz") {
14     item.placeCode = "深";
15   }
16 }
17 写个for循环遍历一下，从第一个对象开始，发现对应的placeCode是sh则更新成文字沪，发现对应的placeCode是sz则更新成文字深，一直到最后一个对象

转载于:https://www.cnblogs.com/yixiaoyang-/p/9989831.html