检查JQuery是否存在DIV ID [英] Check if a DIV id exists with JQuery

问题描述

我正在使用Javascript来测试文档中是否存在ID为"test_div"的DIV.

Using Javascript I'm trying to test whether or not a DIV with the id "test_div" exists in the document.

我正在使用

if (getElementById("test_div"))

在下面的脚本中

检查DIV是否存在于文档中.但是，它不起作用.我对JavaScript没有太多的经验；但是从我所做的研究来看，似乎我的问题可能与嵌套函数有关.

in the below script to check if the DIV exists in the document. However it does not work. I don't have very much experience with Javascript; but from the research I have done it seems like my problem might have something to do with the nested function.

如果删除

if (getElementById("test_div"))

有没有人知道如何从函数中检查文档ID是否为"test_div"的DIV，如下所示?

Does anyone know how to check if a DIV with the id "test_div" exists in the document from within the function as shown below?

<div id="test_div"></div>

<script>
function loadInfo(){
var req = new Request({
    method:'get',
    url:'getinfo.php,
    noCache: true,
    onRequest: function(){

        if (getElementById("test_div")) {
            $('test_div').set('html', 'loading data');
        }

    },  
    onComplete:function(responseText, responseHtml){
        if (JSON.decode(responseText) != null){
            var data = JSON.decode(responseText);

            if (getElementById("test_div")) {
                $('test_div').set('html', data['test_div']);
            }

        }   
    },
    onFailure: function(){

        if (getElementById("test_div")) {
            $('test_div').set('html', '-');
        }

    }           
}).send();  
}
window.addEvent('domready', function(){
loadInfo();
});
</script>

推荐答案

您将必须执行document.getElementById(id).但是，看看您如何使用jquery-您还可以执行$(id).length > 0来检查元素是否存在

You would have to do document.getElementById(id). But seeing how you are using jquery - you could also do $(id).length > 0 to check if the element exists

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