How do I add a function to an element via jQuery?

I want to do something like this:

$('.dynamicHtmlForm').validate = function() {
  return true;
}

$('.dynamicHtmlForm .saveButton').click(function() {
  if (!$(this).closest('.dynamicHtmlForm').validate()) {
    return false;
  }

  return true;
});

And then when I have a form of class dynamicHtmlForm, I w开发者_JS百科ant to be able to provide a custom validate() function:

$('#myDynamicHtmlForm').validate = function() {
  // do some validation

  if (there are errors) {
    return false;
  }

  return true;
}

But I get this when I do this:

$(this).closest(".dynamicHtmlForm").validate is not a function

Is what I've described even possible? If so, what am I doing wrong?

Yes, it is technically possible. You will need to reference the element itself, however, and not the jQuery collection. This should work:

$('.dynamicHtmlForm').each(function (ix,o) {
  o.validate = function() {
    return true;
  }
});

$('.dynamicHtmlForm .saveButton').click(function() {
  if ($(this).closest('.dynamicHtmlForm')[0].validate()) {
    return false;
  }

  return true;
}

jQuery.fn.validate = function(options) {

   var defaults = {
       validateOPtions1 : '',
       validateOPtions2 : ''
   };

   var settings = $.extend({}, defaults, options);
   return this.each(function() {      
       // you validation code goes here
   });
};

$(document).ready(function() {

   $('selector').click(function() {

       $('some selector').validate();

       // or if you used any options in your code that you
       // want the user to enter. then you go :    
       $('some selector').validate({
            validateOPtions1: 'value1',
            validateOPtions2: 'value2'
       });

   });

});

You're not adding the function to the element, you're adding it to the jQuery wrapper around the element. Every time you pass a selector to jQuery, it will create a new wrapper for the found elements:

$('#myEl'); // gives a jQuery wrapper object
$('#myEl'); // creates another jQuery wrapper object

If you save the wrapped element to a variable and use that later, it would be a different story because you're accessing the saved jQuery wrapper object.

var dynamicHtmlForm = $('.dynamicHtmlForm');
dynamicHtmlForm.validate = function() {
  return true;
}

$('.dynamicHtmlForm .saveButton').click(function() {
  if (dynamicHtmlForm.validate()) {
    return false;
  }

  return true;
}

You could also add the function directly to the element using

$('.dynamicHtmlForm')[0].validate = function () { return true; }

// and later...
if (!$(this).closest('.dynamicHtmlForm')[0].validate())

Or you could look at extending jQuery properly by writing a plugin.