javascript - JS 数组 - 如何构建数组

Question

    var adList = new Array();
    adList[0]["img"] = 'http://www.gamer-source.com/image/media/screenshot/thumbnail/489.jpg';/*
    adList[0]["h3"] = 'Product title2';
    adList[0]["button"]["link"] = '#link-url';
    adList[0]["button"]["text"] = 'Buy now';
    adList[0]["h3"] = 'asdfasdfasdf';

    adList[1]["img"] = 'http://www.gamer-source.com/image/media/screenshot/thumbnail/489.jpg';
    adList[1]["h3"] = 'Product title2';
    adList[1]["button"]["link"] = '#link-url';
    adList[1]["button"]["text"] = 'Buy now';
    adList[1]["h3"] = 'asdfasdfasdf';

我遇到错误 adList[0] is undefined，我不能像这样定义数组吗？在为它分配变量之前，是否必须将 adList[0] 指定为数组？

Answer 1

问题是您试图引用尚未分配值的 adList[0]。因此，当您尝试访问 adList[0]['img'] 的值时，会发生这种情况:

adList           -> Array
adList[0]        -> undefined
adList[0]["img"] -> Error, attempting to access property of undefined.

尝试使用数组和对象文字符号来定义它。

adList = [{
    img: 'http://www.gamer-source.com/image/media/screenshot/thumbnail/489.jpg',
    h3: 'Product title 1',
    button: {
        text: 'Buy now',
        url: '#link-url'
    }
},
{
    img: 'http://www.gamer-source.com/image/media/screenshot/thumbnail/489.jpg',
    h3: 'Product title 2',
    button: {
        text: 'Buy now',
        url: '#link-url'
    }
}];

或者您可以简单地分别定义 adList[0] 和 adList[1] 并使用您的旧代码:

var adList = new Array();
adList[0] = {};
adList[1] = {};
adList[0]["img"] = 'http://www.gamer-source.com/image/media/screenshot/thumbnail/489.jpg';
... etc etc