如何访问外部JavaScript文件中的DOM对象？
[英]How can I access DOM objects in an external JavaScript file?
问题描述
I'm using an external JavaScript file to access DOM objects with in my documents. 
我正在使用外部JavaScript文件来访问文档中的DOM对象。 The problem is that jQuery doesn't seem to have access if it's an externally loaded file. 问题是，如果jQuery是外部加载的文件，则它似乎无权访问。 My code looks like: 我的代码如下：
<html>
<head>
</head>
<body>
<div id="domToChange" someAttribute="hi"></div>
<script src="officialJqueryLibrary"></script>
<script src="myJS.js"></script>
</body>
</html>
///////// myJS.js file
// Returns undefined
$('#domToChange').attr('someAttribute');
The DOM selector doesn't seem to find my div when the JavaScript file is loaded externally. 从外部加载JavaScript文件时，DOM选择器似乎找不到我的div。 However everything works when I place it inside the HTML document itself. 但是，当我将其放置在HTML文档本身中时，一切正常。 How can I give DOM access to my JavaScript file? 如何授予DOM访问我的JavaScript文件的权限？
4 个解决方案
解决方案1
0 2013-08-14 22:43:54
You have to enclose the code like this: 您必须封装如下代码：
$(function(){
$('#domToChange').attr('someAttribute');
});
So that the code is executed when the DOM is ready. 以便在DOM准备就绪时执行代码。
解决方案2
0 2013-08-14 22:44:11
You should wrap all your DOM related code into 您应该将所有与DOM相关的代码包装到
$(function() {
//Code
});
Then the code gets executed when the DOM is fully loaded. 然后，当DOM完全加载时，将执行代码。
解决方案3
0 2013-08-14 22:59:13
Try getting the value for your attribute, like so: 尝试获取属性的值，如下所示：
$('#domToChange').attr('someattribute');
//or
$('#domToChange').attr('someAttribute'); // i know you've tried this, but pls check demo
Demo here . 演示在这里 。 On my machine, browser Chrome Version 28.0.1500.95 m, it just works fine. 在我的机器上，浏览器Chrome版本28.0.1500.95 m，它运行良好。
解决方案4
0 2013-08-15 00:26:19
OK, this is a hit and miss kind of thing (but I believe it be an accurate explanation), but the real explanation for why it is happening lies here. 好的，这是一件偶然的事情（但我相信这是一个准确的解释），但真正的解释却在这里。
You need to understand that jQuery is an object that is initialized . 您需要了解jQuery是已初始化的对象 。 So the jQuery object takes time to initiatize. 因此，jQuery对象需要花费一些时间来初始化。 As it says, 就像说的那样
is very important to make the distinction between jQuery object and native DOM elements.
So it is not necessary that the jQuery object gets initialized at the same time the DOM gets initialized. 因此，不必在初始化DOM的同时初始化jQuery对象。
Also, all scripts that are passed have a defer attribute. 另外，所有传递的脚本都具有defer属性。 This is mostly browser dependent. 这主要取决于浏览器。
As it says, 就像说的那样
When set, this boolean attribute provides a hint to the user agent that the script is not going to generate any document content (eg, no "document.write" in javascript) and thus, the user agent can continue parsing and rendering.
And it can sometimes delay the execution of the script. 而且有时可能会延迟脚本的执行。 Hence the different result according to different people. 因此，根据不同的人会有不同的结果。
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