How to create a jQuery function to return a bool?

Question

How can I create a jQuery function like

$.MyFunction(/*optional parameter*/)?

which will return a bool?

note:

I've tried this:

jQuery.fn.isValidRequest = function (options) {

    return true;
}

// I'm contending with Prototype, so I have to use this    
jQuery(document).ready(function ($) {    

    // and jQuery 1.2.6, supplied by the client - long story
    $('a').livequery('click', function () {

        alert($.isValidRequest("blah"));
        return false;
    });
});

but it crashes on the alert() with

Microsoft JScript runtime error: Object doesn't support this property or method

This is what worked in the end:

jQuery.isValidRequest = function (options) {

    return true;
}

Wait - you have two versions of jQuery active at once? What symbols are you using to differentiate between them? Or do you just mean that you're using jQuery 1.2.6 for this. — Shog9
– Shog9, Commented Aug 13, 2010 at 20:53
If you're defining your function in $.fn, Then you'll need to call it there $.fn.isValidRequest("blah") or from a jQuery object $('selector').isValidRequest(). Doesn't seem like that's what you want. If it is just more of a utility, then define it under jQuery as in jQuery.isValidRequest = function(.... — user113716
– user113716, Commented Aug 13, 2010 at 20:53
@Shog9 - I think OP was explaining (in the code comment) why he's using livequery instead of live(). I could be wrong, though. — user113716
– user113716, Commented Aug 13, 2010 at 20:58
@patrick: you may be right. Good catch on the $.fn vs $. scenario... I tend to forget that people use the latter. — Shog9
– Shog9, Commented Aug 13, 2010 at 21:01
@patrick, @Shog: yeah, I'm using 1.2.6. That's why I need livequery. Also, the client has Prototype in the HTML wrapper they supply us with, into which we inject our content. — DaveDev
– DaveDev, Commented Aug 13, 2010 at 21:01

Shog9 · Accepted Answer · 2010-08-13 20:58:02Z

6

For a function you intend to call from jQuery instances, you'd define it like this:

$.fn.MyFunction = function(options)
{
  // return bool here
};

And call like any other jQuery method:

$('selector').MyFunction(...);

A function intended to be called from the global jQuery object (or its $ alias) would be attached directly to that object:

$.MyFunction = function(options)
{
  // return bool here
};

And call the same way:

$.MyFunction(...);

Note that I've used $.fn for brevity - this can cause problems if jQuery is prevented from using the $ alias for compatibility with other libraries. The recommended way to attach a plugin function is:

(function($) // introduce scope wherein $ is sure to equate to jQuery
{ 
  $.fn.MyFunction = function(options) 
  { 
    // return bool here 
  };
})(jQuery); // conclude plugin scope

Note also that most jQuery functions return this, to enable chaining; if you opt to return some other value, you'll be unable to do this. Be sure to document clearly that your function returns a boolean, or you'll find yourself wondering why e.g. $("...").MyFunction().hide() breaks later on.

You can read more about extending jQuery here:
Extending jQuery – plugin development
and in the jQuery documentation:
Plugins/Authoring

edited Aug 13, 2010 at 20:58

Shog9

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answered Aug 13, 2010 at 20:27

ovais.tariq

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4 Comments

Shog9 Over a year ago

Style note: by using $.fn instead of jQuery.fn, you'll introduce errors if $ is used by some other library (via jQuery.noConflict()).

ovais.tariq Over a year ago

i had used $ for bravity's sake, the recommended way is (function($) { $.fn.MyFunction = function(options) { // return bool here } })(jQuery);

DaveDev Over a year ago

This doesn't work.. I've updated the question to reflect, thanks

Shog9 Over a year ago

fair enough - I've taken the liberty of adding your comment and portions of my own answer to this answer, as there are rather too many answers here already.

Ian Henry · Accepted Answer · 2010-08-13 20:26:20Z

1

$.fn.MyFunction = function(param) {
   if(arguments.length > 0)
      return true;
   else
      return false;
}

answered Aug 13, 2010 at 20:26

Ian Henry

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Comments

Lloyd · Accepted Answer · 2010-08-13 20:25:23Z

0

http://blogs.microsoft.co.il/blogs/basil/archive/2008/09/22/defining-your-own-functions-in-jquery.aspx

You can still just return like in plain JavaScript true/false for boolean parameters.

answered Aug 13, 2010 at 20:25

Lloyd

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Comments

pixeline · Accepted Answer · 2010-08-13 20:25:30Z

0

$.myfunction(options){
return options.isThisTrue;
}

usage:

       $(document).ready(function(){ 
         var isThisTrue = $.myfunction({isthisTrue: false});
         // isThisTrue is false
        });

answered Aug 13, 2010 at 20:25

pixeline

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Comments

John Strickler · Accepted Answer · 2010-08-13 20:25:51Z

0

$.fn.MyFunction = function(params) { return true; }

answered Aug 13, 2010 at 20:25

John Strickler

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