How to Avoid Unnecessary JavaScript Execution in Rails 3.1?

Page-Specific JavaScript in Rails 3.1

Rails 3.1's default merging behavior of JavaScript into a single file raises concerns about page-specific code being executed unnecessarily. To address this, consider the following approaches:

Controller-Specific JavaScript:

The Asset Pipeline documentation provides a solution for controller-specific JavaScript. For instance, a ProjectsController would have corresponding asset files at app/assets/javascripts/projects.js.coffee and app/assets/stylesheets/projects.css.scss. Unique JavaScript or CSS can be placed within these files and loaded only for the relevant controllers using:

• <%= javascript_include_tag params[:controller] %>
• <%= stylesheet_link_tag params[:controller] %>

ID/Class-Based Code Triggering:

Alternatively, page-specific code can be conditionally executed by checking for the presence of specific IDs or classes. In the JavaScript, check if the corresponding element exists and execute the associated code if found. This ensures that code only runs when the relevant element is present.

Example:

if ($("#search-box").length > 0) {
  // Execute JavaScript for search box
}

Benefits of Conditional Code Triggering:

• Page-specific code executes only when necessary, reducing resource consumption.
• Manual script tags are eliminated, simplifying maintenance and preventing code redundancy.
• Features can be added to multiple pages without manually including code on each page.

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