functions inside or outside jquery document ready

Up until now I just put all my jQuery goodness inside the $(document).ready() function, including simple functions used in certain user interactions.

But functions that don´t require the DOM document to be loaded or are only called afterwards anyway, can be placed outside the $(document).ready() as well. Consider for example a very simple validation function such as:

function hexvalidate(color) {
// Validates 3-digit or 6-digit hex color codes 
 var reg = /^(#)?([0-9a-fA-F]{3})([0-9a-fA-F]{3})?$/;
 return reg.test(color);
}

The function is only called from within the $(document).ready() function though.

What is best practice (syntax, speed); placing such a function inside or outside the jquery document ready function?

Answers:

Answer

Put it inside so it won't pollute the global namespace. It also ensures a faster resolve of the function name because of JavaScript's scope chains.

Put it outside if it's a reusable component so you could easily move it in a separate file and call from different contexts.

Since you already use JQuery, it worths mentioning, that in your case you may want to define hexvalidate as a JQuery plugin outside and then invoke it inside.

Answer

one advantage of putting those functions inside the document ready function is that they don't pollute your global namespace... with the downside that if you need them somewhere else on the page they won't be available.

Answer

If all your functions are only called from within the jQuery(function () { }) block, put them inside it. Otherwise you're needlessly polluting the global namespace, which may lead to conflicts down the road.

Only declare functions globally that are also used by code in other scopes.

Answer

If you're creating a function that needs to be called outside of the scope of the $(document).ready() function, keep it outside of the $(document).ready() function.

Otherwise keep it internal.

Answer

I don't think you should be using any 'just functions' in the first place. In OOP javascript a "function" usually belongs to one of four distinct types:

  • Constructor or an anonymous 'init' closure - used to construct objects. The only type of function that is allowed to be global
  • Method - function that is a part of some object
  • Utility - inner function of a constructor/method, invisible from outside
  • Constant - a functional constant passed as a parameter

e.g.

 (function() { <- init closure

        function helper1() { <- utility }

        globalSomething = {

              foobar: function() { <- method 
                  xyz.replace(/.../, function() { <- constant })

              }
        }
  )()

In your example, 'hexvalidate' is obviously a part of Validator object, which, in turn, can be made a jQuery plugin:

   (function($) {
        $.validate = {
            hexColor: function(color) { ... your code }
            more validators...
        }
     )(jQuery)

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