为什么将 JavaScript 放在页面的页脚中? [英] Why put JavaScript in the footer of a page?

问题描述

所以我最近从 ThemeForest 购买并下载了一个模板.我在本地服务器上设置了模板.我使用 codeigniter 生成了具有下拉菜单的导航.我将菜单中的所有内容都正确编码.我只生成了标题并进行了测试，并意识到下拉菜单不起作用.我花了大约两个小时试图找出我的代码出了什么问题.然后我终于意识到 JavaScript 文件包含在模板的页脚中......我还没有生成.

So I recently bought and downloaded a template from ThemeForest. I set up the template on my local server. I generated the navigation, which has dropdown menus, with codeigniter. I had everything in the menu coded correctly. I only had the header generated and went to test it out and realized the dropdown menus were not working. I spent about two hours trying to figure out what was wrong with my code. Then I finally realized that the JavaScript files were included in the footer of the template... which I had not yet generated.

所以我的问题是……为什么有人会将 JavaScript 文件放在 HTML 页面的页脚中?我认为 JS 只应该位于文件的标题中.对吧?

So my question is... why would someone put JavaScript files in the footer of an HTML page? I thought that JS was only supposed to be located in the header of the file. Right?

推荐答案

您可以通过多种方式将脚本文件加载到网页.

There are different ways you could load a script file to a web page.

但是在页面底部加载脚本有以下优点.

But loading scripts at bottom of you page have the following advantages.

1. 不会阻止任何要加载的 DOM 内容.
2. 所有 DOM 元素都可用于正在加载的脚本.
3. 如果您使用第三方库，例如 jQuery，则可以跳过 $(document).ready(function () {...});，因为 DOM 已经加载.

1. Will not block any DOM content to be loaded.
2. All the DOM elements will be available for the scripts that are being loaded.
3. If you are using third-party libraries such as jQuery, you can skip the $(document).ready(function () {...}); as the DOM is already loaded.

希望这会有所帮助.

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