[javascript] Where do you include the jQuery library from? Google JSAPI? CDN?

There are a few ways to include jQuery and jQuery UI and I'm wondering what people are using?

• Google JSAPI
• jQuery's site
• your own site/server
• another CDN

I have recently been using Google JSAPI, but have found that it takes a long time to setup an SSL connection or even only to resolve google.com. I have been using the following for Google:

<script src="https://www.google.com/jsapi"></script>
<script>
google.load('jquery', '1.3.1');
</script>

I like the idea of using Google so it's cached when visiting other sites and to save bandwidth from our server, but if it keeps being the slow portion of the site, I may change the include.

What do you use? Have you had any issues?

Edit: Just visited jQuery's site and they use the following method:

<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.3/jquery.min.js"></script>

Edit2: Here's how I've been including jQuery without any problems for the last year:

<script src="//ajax.googleapis.com/ajax/libs/jquery/1.4.3/jquery.min.js"></script>

The difference is the removal of http:. By removing this, you don't need to worry about switching between http and https.

In head:

  (function() {
    var jsapi = document.createElement('script'); jsapi.type = 'text/javascript'; jsapi.async = true;
    jsapi.src = ('https:' == document.location.protocol ? 'https://' : 'http://') + 'www.google.com/jsapi?key=YOUR KEY';
    (document.getElementsByTagName('head')[0] || document.getElementsByTagName('head')[0]).appendChild(jsapi);
  })();

End of Body:

<script type="text/javascript">
google.load("jquery", "version");
</script>

I just include the latest version from the jQuery site: http://code.jquery.com/jquery-latest.pack.js It suits my needs and I never have to worry about updating.

EDIT:For a major web app, certainly control it; download it and serve it yourself. But for my personal site, I could not care less. Things don't magically disappear, they are usually deprecated first. I keep up with it enough to know what to change for future releases.

I wouldn't want any public site that I developed to depend on any external site, and thus, I'd host jQuery myself.

Are you willing to have an outage on your site when the other (Google, jquery.com, etc.) goes down? Less dependencies is the key.

Pros: Host on Google has benefits

• Probably faster (their servers are more optimised)
• They handle the caching correctly - 1 year (we struggle to be allowed to make the changes to get the headers right on our servers)
• Users who have already had a link to the Google-hosted version on another domain already have the file in their cache

Cons:

• Some browsers may see it as XSS cross-domain and disallow the file.
• Particularly users running the NoScript plugin for Firefox

I wonder if you can INCLUDE from Google, and then check the presence of some Global variable, or somesuch, and if absence load from your server?

One reason you might want to host on an external server is to work around the browser limitations of concurent connections to particular server.

However, given that the jQuery file you are using will likely not change very often, the browser cache will kick in and make that point moot for the most part.

Second reason to host it on external server is to lower the traffic to your own server.

However, given the size of jQuery, chances are it will be a small part of your traffic. You should probably try to optimize your actual content.

Here some useful resource, hope can help you to chose your CDN. MS has recently add a new domain for delivery Libraries trough their CDN.

Old Format: http://ajax.microsoft.com/ajax/jQuery/jquery-1.5.1.js New Format: http://ajax.aspnetcdn.com/ajax/jQuery/jquery-1.5.1.js

This should not send all cookies for microsoft.com. http://www.asp.net/ajaxlibrary/cdn.ashx#Using_jQuery_from_the_CDN_11

Here some statistics about most popular technology used on the web across all technology. http://trends.builtwith.com/

Hope can help you to choose.

I host it with my other js files on my own server, and, that's that point, combine and minify them (with django-compresser, here, but that's not the point) to be served as just one js file, with everything the site needs put into it. You'll need to serve your own js files anyway, so I see no reason to not add the extra jquery bytes there too - some more kbs are much more cheaper to transfer, than more requests to be made. You are not dependent to anyone, and as soon as your minified js is cached, you're super fast as well.

On first load, a CDN based solution might win, because you must load the additional jquery kilobytes from your own server (but, without an additional request). I doubt the difference is noticable, though. And then, on a first load with cleared cache, your own hosted solution will probably always be much faster, because of more requests (and DNS lookups) needed, to fetch the CDN jquery.

I wonder how this point is almost never mentioned, and how CDNs seem to take over the world :)

jQuery 1.3.1 min is only 18k in size. I don't think that's too much of a hit to ask on the initial page load. It'll be cached after that. As a result, I host it myself.

If I am responsible for the 'live' site I better be aware of everything that is going on and into my site. For that reason I host the jquery-min version myself either on the same server or a static/external server but either way a location where only I (or my program/proxy) can update the library after having verified/tested every change

I have to vote -1 for the libraries hosted on Google. They are collecting data, google analytics style, with their wrappers around these libraries. At a minimum, I don't want a client browser doing more than I'm asking it to do, much less anything else on the page. At worse, this is Google's "new version" of not being evil -- using unobtrusive javascript to gather more usage data.

Note: if they've changed this practice, super. But the last time I considered using their hosted libraries, I monitored the outbound http traffic on my site, and the periodic calls out to google servers were not something I expected to see.

In addition to people who advices to host it on own server, I'd proposed to keep it on separate domain (e.g. static.website.com) to allow browsers to load it into separate from other content thread. This tip also works for all static stuff, say images and css.

There are a few issues here. Firstly, the async load method you specified:

<script type="text/javascript" src="https://www.google.com/jsapi"></script>
<script type="text/javascript">
  google.load('jquery', '1.3.1');
  google.setOnLoadCallback(function() {
    // do stuff
  });
</script>

has a couple of issues. Script tags pause the page load while they are retrieved (if necessary). Now if they're slow to load this is bad but jQuery is small. The real problem with the above method is that because the jquery.js load happens independently for many pages, they will finish loading and render before jquery has loaded so any jquery styling you do will be a visible change for the user.

The other way is:

<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.3.1/jquery.min.js"></script>

Try some simple examples like, have a simple table and change the background of the cells to yellow with the setOnLoadCallback() method vs $(document).ready() with a static jquery.min.js load. The second method will have no noticeable flicker. The first will. Personally I think that's not a good user experience.

As an example run this:

<html>
<head>
  <title>Layout</title>
  <style type="text/css">
    .odd { background-color: yellow; }
  </style>
</head>
<body>
<table>
  <tr><th>One</th><th>Two</th></tr>
  <tr><td>Three</td><td>Four</td></tr>
  <tr><td>Five</td><td>Six</td></tr>
  <tr><td>Seven</td><td>Nine</td></tr>
  <tr><td>Nine</td><td>Ten</td></tr>
</table> 
<script src="http://www.google.com/jsapi"></script>
<script>
  google.load("jquery", "1.3.1");
  google.setOnLoadCallback(function() {
    $(function() {
      $("tr:odd").addClass("odd");
    });
  });
</script>
</body>
</html>

You (should) see the table appear and then the rows go yellow.

The second problem with the google.load() method is that it only hosts a limited range of files. This is a problem for jquery since it is extremely plug-in dependent. If you try and include a jquery plugin with a <script src="..."> tag and google.load() the plug-in will probably fail with messages of "jQuery is not defined" because it hasn't loaded yet. I don't really see a way around this.

The third problem (with either method) is that they are one external load. Assuming you have some plugins and your own Javascript code you're up to a minimum of two external requests to load your Javascript. You're probably better off getting jquery, all relevant plug-ins and your own code and putting it into one minified file.

From Should You Use Google's Ajax Libraries API for Hosting?:

As to load times, you're actually loading two scripts - the jsapi script and the mootools script (the compressed version from above). So that is two connections, rather than one. In my experience, I found that the load time was actually 2-3 times slower than loading from my own personal shared server, even though it was coming from Google, and my version of the compressed file was a couple of K larger than Google's. This, even after the file had loaded and (presumably) cached. So for me, since the bandwidth doesn't matter much, isn't going to matter.

Lastly you have the potential problem of a paranoid browser flagging the request as some sort of XSS attempt. It's not typically a problem with default settings but on corporate networks where the user may not have control over which browser they use let alone the security settings you may have a problem.

So in the end I can't really see me using the Google AJAX API for jQuery at least (the more "complete" APIs are a different story in some ways) much except to post examples here.

I will add this as a reason to locally host these files.

Recently a node in Southern California on TWC has not been able to resolve the ajax.googleapis.com domain (for users with IPv4) only so we are not getting the external files. This has been intermittant up until yesterday (now it is persistant.) Because it was intermittant, I was having tons of problems troubleshooting SaaS user issues. Spent countless hours trying to track why some users were having no issues with the software, and others were tanking. In my usual debugging process I'm not in the habit of asking a user if they have IPv6 turned off.

I stumbled on the issue because I myself was using this particular "route" to the file and also am using only IPV4. I discovered the issue with developers tools telling me jquery wasn't loading, then started doing traceroutes etc... to find the real issue.

After this, I will most likely never go back to externally hosted files because: google doesn't have to go down for this to become a problem, and... any one of these nodes can be compromised with DNS hijacking and deliver malicious js instead of the actual file. Always thought I was safe in that a google domain would never go down, now I know any node in between a user and the host can be a fail point.

I might be old-school about this, but I still frown on hotlinking. Maybe Google is the exception, but in general, it's really just good manners to host the files on your own server.

If you want to use Google, the direct link may be more responsive. Each library has the path listed for the direct file. This is the jQuery path

<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.3.1/jquery.min.js"></script>

Just reread your question, is there a reason your are using https? This is the script tag Google lists in their example

<script src="http://www.google.com/jsapi"></script>