javascript_include_tag(*sources) public

Returns an html script tag for each of the sources provided. You can pass in the filename (.js extension is optional) of javascript files that exist in your public/javascripts directory for inclusion into the current page or you can pass the full path relative to your document root. To include the Prototype and Scriptaculous javascript libraries in your application, pass :defaults as the source. When using :defaults, if an application.js file exists in your public javascripts directory, it will be included as well. You can modify the html attributes of the script tag by passing a hash as the last argument. 

  javascript_include_tag "xmlhr" # =>
    <script type="text/javascript" src="/javascripts/xmlhr.js"></script>

  javascript_include_tag "common.javascript", "/elsewhere/cools" # =>
    <script type="text/javascript" src="/javascripts/common.javascript"></script>
    <script type="text/javascript" src="/elsewhere/cools.js"></script>

  javascript_include_tag :defaults # =>
    <script type="text/javascript" src="/javascripts/prototype.js"></script>
    <script type="text/javascript" src="/javascripts/effects.js"></script>
    ...
    <script type="text/javascript" src="/javascripts/application.js"></script> *see below
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July 20, 2010
4 thanks

When scripts don't end in .js

For example, Google Custom Search’s URL is http://www.google.com/jsapi

It’s an ugly hack, but works:

= javascript_include_tag('http://www.google.com/jsapi').sub('.js', '')
December 2, 2009
2 thanks

IE GOTCHA - multiple javascript_include_tags with cache => true

If you have multiple lines of javascript_include_tag ‘jsfile’, :cache => true, IE does not load them all (though it seems Firefox and Safari do). And the error won’t show up until you’re in production (since that’s only when caching kicks in.)

You should include them all on one line:

javascript_include_tag 'file1.js', 'file2.js', 'file3.js', :cache => 'myfiles'
July 10, 2010
2 thanks

Re: IE GOTCHA

@insane-dreamer

That has nothing to do with IE. When you specify :cache => true you are saying that the files referenced should be saved to a file called all.js. When the script encounters the next line, it will overwrite the same file with the new contents.

Caching is not compressing, it doesn’t make sense to do with individual files, but it can make sense some times. I someone wants to do it, just specify a name for the cached file:

javascript_include_tag 'layout', 'typography', :cache => 'base'
javascript_include_tag 'admin/layout', 'admin/extras', :cache => 'admin'