如何在jQuery中检查HTML对象是否为null？

Question

我试图用HTML查找HTML中的对象.

function getHats() {
    $.get('http://www.roblox.com/User.aspx?ID=1',
        function parse(data) {
            var id1 = $(data).find('#ctl00_cphRoblox_rbxUserAssetsPane_UserAssetsDataList_ctl09_AssetThumbnailHyperLink');
            hatname1 = id1.attr('title');
            hatlink1 = "http://www.roblox.com" + id1.attr('href');
            hatpic1 = id1.find('img').attr('src');
            var lim1 = id1.parent('.AssetThumbnail').find('div');
            if(!lim1) {
                hatlim1 = true;
                alert("Null")
            }else{
                hatlim1 = false;
            };
        }
    );
};

它总是弹出警报.

Answer 1

使用长度 - 但你不必明确它:

if (lim1.length) {
    // lim1 has a length! And it's not 0!
} else {
    // arg, lim1 has a length of 0
}

等价地,否定运算符!将正常工作.

if (!lim1.length) {
    // arg!
}