javascript jQuery CDN 未在 LocalHost 上加载
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jQuery CDN is not loading on LocalHost
提问by FluxEngine
I have a jquery cdn loading from the following:
我有一个 jquery cdn 从以下加载：
<head>
.
.
<script src="//ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script>
</head>
then in the body I have my source for my script
然后在正文中我有我的脚本的来源
<body>
.
.<script src="app.js"></script>
</body>
This is all on local, but when I view in browser I keep getting the following errors in console:
这一切都在本地，但是当我在浏览器中查看时，我不断在控制台中收到以下错误：
GET file://ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js
Uncaught ReferenceError: $ is not defined
I assume this is saying the jQuery function "$..." is undefined because there is an error in GET of the CDN, why would this be happening on local?
我认为这是说 jQuery 函数“$...”未定义，因为 CDN 的 GET 中存在错误，为什么会在本地发生这种情况？
回答by JJJ
You aren't actually running on localhost (http://localhost) but on the local file system (file:///path/to/whatever.html). The protocol is copied with the //link to file://ajax.googleapis.comwhich of course doesn't exist.
您实际上不是在 localhost ( http://localhost) 上运行，而是在本地文件系统 ( file:///path/to/whatever.html) 上运行。该协议与当然不存在的//链接一起复制file://ajax.googleapis.com。
You should set up a server on your computer so that you'd have an actuallocalhost accessed with the http protocol. It would have other benefits as well since browsers act a bit differently also in other regards when the page is loaded directly from the file system.
您应该在您的计算机上设置一个服务器，以便您可以使用 http 协议访问一个实际的本地主机。它还有其他好处，因为当页面直接从文件系统加载时，浏览器在其他方面的行为也会有所不同。
回答by Adam Clason
Have you tried removing the "//" at the beginning of the "src" attribute and instead using "http://"? It is probably appending "localhost" to the beginning of the URL because of those slashes.
您是否尝试删除“src”属性开头的“//”而使用“http://”？由于这些斜杠，它可能将“localhost”附加到 URL 的开头。
回答by Googol
I've answered a similar question in How to use Bootstrap CDN?and, as Juhana said, the problem is the missing protocol when loading jQuery.
我在如何使用 Bootstrap CDN 中回答了类似的问题？而且，正如 Juhana 所说，问题在于加载 jQuery 时缺少协议。
The protocol-less CDN works when you are using http or https, because browsers will add the prefix to the jQuery URL with it.
当您使用 http 或 https 时，无协议 CDN 有效，因为浏览器会将前缀添加到 jQuery URL 中。
But when using a local html file, the missing protocol will be file:and browsers will not be able to find jQuery in something like file://ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.jsfailing to load it. In that case you must add the protocol manually, which is a pitty if you finally use the page on-line because a protocol-less URL is better and more cache friendly (http://encosia.com/cripple-the-google-cdns-caching-with-a-single-character/).
但是当使用本地 html 文件时，缺少的协议将是file:浏览器将无法在无法file://ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js加载它的情况下找到 jQuery 。在这种情况下，您必须手动添加协议，如果您最终在线使用该页面，这是一个遗憾，因为无协议 URL 更好，缓存更友好（http://encosia.com/cripple-the-google- cdns-caching-with-a-single-character/）。
