Question

I am writing a javascript file for an ASP.NET web app used by many people. This file will use jQuery, so to ensure I can safely use the $ alias, the file is structured like this:

(function ($) {
  // My javascript here can safely use the $ alias
})(jquery);

However, my Firebug console is showing the error “jQuery is not defined”. I made sure the script tag for this file comes after the script tag for jQuery, but clearly this script is running before jQuery is ready.

How can I ensure the script runs after jQuery is ready?

Answer 1

Identifiers in Javascript are case-sensitive.

The variable jquery doesn’t exist, but jQuery does.

(function ($) {
  // My javascript here can safely use the $ alias
})(jQuery);

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To address your doubts about when scripts are executed:

The execution of scripts waits for external scripts to be loaded.

The jQuery script will always be loaded and executed before the browser continues with script later in the page. (Unless of course the jQuery script fails to load altogether.)