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Javascript Include Tag Best Practice in a Rails Application

Asked 2008-12-23T21:48:34.407
61

Say I need to call a javascript file in the <head> of an ERb template. My instinct is to do the usual:

<head>
<%= javascript_include_tag :defaults %> <!-- For example -->
</head>

in my application's layout. The problem of course becoming that these javascript files are loaded into every page in my application, regardless of whether or not they are needed for the page being viewed.

So what I'm wondering is if there's a good way of loading a javascript into the the headers of, for example, all ERb templates found only in a specific directory.

javascript ruby-on-rails header rjs
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3 Answers

6

I feel there's nothing wrong including all yr defaults since they can then be cached on user's browser.

answered 2008-12-24T14:51:06.340
3

I would suggest not to add javascript in the header as it causes to load the page slower. Rather load the js at the bottom of the page, which is faster. http://developer.yahoo.com/performance/rules.html#js_bottom

<body>
 ....
  <%= yield(:js) -%>
</body>

And send it there from a view:

<%- content_for(:js) do -%>
  <%= javascript_include_tag :defaults -%>
<%- end -%>
answered 2013-06-19T05:51:40.110
1

I usually have the following in the layout file:

<head>
  <%= javascript_include_tag :defaults %> <!-- For example -->
  <%= @extra_head_content %>
</head>

And then in the views:

<% (@extra_head_content ||= "") += capture do %>
  <%= other_content %>
<% end %>

See the API documentation for #capture

answered 2008-12-23T21:56:04.483

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