CODEWITHSUNDEEP
javascriptjqueryfunction
Eduardo Ponce de Leon
Eduardo Ponce de Leon

Reputation: 9696

How to create a jQuery function (a new jQuery method or plugin)?

I know that in JavaScript the syntax is as follows:

function myfunction(param){
  //some code
}

Is there a way to declare a function in jQuery that can be added to an element? For example:

$('#my_div').myfunction()

Upvotes: 230

Views: 785316

Answers (14)

Kamlesh
Kamlesh

Reputation: 6135

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>Define a function in jQuery</title>
<script src="https://code.jquery.com/jquery-3.5.1.min.js"></script>
<script>
$(document).ready(function() {
    $.fn.myFunction = function() { 
        alert('You have successfully defined your function!'); 
    }
    $(".call-btn").click(function(){
        $.fn.myFunction();
    });
});
</script> 
</head>
<body>
    <button type="button" class="call-btn">Click Here</button>
</body>
</html>

Upvotes: 1

user8903269
user8903269

Reputation:

You can always do this:

jQuery.fn.extend({
   myfunction: function(param){
       // code here
   },
});
OR
jQuery.extend({
   myfunction: function(param){
       // code here
   },
});
$(element).myfunction(param);

Upvotes: 3

Bob Stein
Bob Stein

Reputation: 17204

Create a "colorize" method:

$.fn.colorize = function custom_colorize(some_color) {
    this.css('color', some_color);
    return this;
}

Use it:

$('#my_div').colorize('green');

This simple-ish example combines the best of How to Create a Basic Plugin in the jQuery docs, and answers from @Candide, @Michael.

Upvotes: 4

Pevara
Pevara

Reputation: 14310

In spite of all the answers you already received, it is worth noting that you do not need to write a plugin to use jQuery in a function. Certainly if it's a simple, one-time function, I believe writing a plugin is overkill. It could be done much more easily by just passing the selector to the function as a parameter. Your code would look something like this:

function myFunction($param) {
   $param.hide();  // or whatever you want to do
   ...
}

myFunction($('#my_div'));

Note that the $ in the variable name $param is not required. It is just a habit of mine to make it easy to remember that that variable contains a jQuery selector. You could just use param as well.

Upvotes: 89

Chintan Thummar
Chintan Thummar

Reputation: 1552

Simplest example to making any function in jQuery is

jQuery.fn.extend({
    exists: function() { return this.length }
});

if($(selector).exists()){/*do something here*/}

Upvotes: 1

user1619962
user1619962

Reputation: 374

$(function () {
    //declare function 
    $.fn.myfunction = function () {
        return true;
    };
});

$(document).ready(function () {
    //call function
    $("#my_div").myfunction();
});

Upvotes: 9

Novasol
Novasol

Reputation: 947

You can also use extend (the way you create jQuery plugins):

$.fn.extend(
{
    myfunction: function () 
    {
    },

    myfunction2: function () 
    {
    }
});

Usage: 

$('#my_div').myfunction();

Upvotes: 7

Roland Mai
Roland Mai

Reputation: 31077

From the Docs:

(function( $ ){
   $.fn.myfunction = function() {
      alert('hello world');
      return this;
   }; 
})( jQuery );

Then you do 

$('#my_div').myfunction();

Upvotes: 326

Michael
Michael

Reputation: 1207

You can write your own jQuery plugins(function which can be called on selected elements) like below:

(function( $ ){
    $.fn.myFunc = function(param1, param2){
        //this - jquery object holds your selected elements
    }
})( jQuery );


Call it later like:

$('div').myFunc(1, null);

Upvotes: 6

Paul D. Waite
Paul D. Waite

Reputation: 98786

Yup — what you’re describing is a jQuery plugin.

To write a jQuery plugin, you create a function in JavaScript, and assign it to a property on the object jQuery.fn.

E.g.

jQuery.fn.myfunction = function(param) {
    // Some code
}

Within your plugin function, the this keyword is set to the jQuery object on which your plugin was invoked. So, when you do:

$('#my_div').myfunction()

Then this inside myfunction will be set to the jQuery object returned by $('#my_div').

See http://docs.jquery.com/Plugins/Authoring for the full story.

Upvotes: 10

Richard Dalton
Richard Dalton

Reputation: 35793

To make a function available on jQuery objects you add it to the jQuery prototype (fn is a shortcut for prototype in jQuery) like this:

jQuery.fn.myFunction = function() {
    // Usually iterate over the items and return for chainability
    // 'this' is the elements returns by the selector
    return this.each(function() { 
         // do something to each item matching the selector
    }
}

This is usually called a jQuery plugin.

Example - http://jsfiddle.net/VwPrm/

Upvotes: 15

jbabey
jbabey

Reputation: 46647

It sounds like you want to extend the jQuery object via it's prototype (aka write a jQuery plugin). This would mean that every new object created through calling the jQuery function ($(selector/DOM element)) would have this method.

Here is a very simple example:

$.fn.myFunction = function () {
    alert('it works');
};

Demo

Upvotes: 2

Richard Neil Ilagan
Richard Neil Ilagan

Reputation: 14747

While there is a plethora of documentation / tutorials out there, the simple answer for your question is this:

// to create a jQuery function, you basically just extend the jQuery prototype
// (using the fn alias)

$.fn.myfunction = function () {
    // blah
};

Inside that function, the this variable corresponds to the jQuery wrapped set you called your function on. So something like:

$.fn.myfunction = function () {
    console.log(this.length);
};

$('.foo').myfunction();

... will flush to the console the number of elements with the class foo.

Of course, there is a bit more to semantics than that (as well as best practices, and all that jazz), so make sure you read up on it.

Upvotes: 44

Jamiec
Jamiec

Reputation: 136074

Yes, methods you apply to elements selected using jquery, are called jquery plugins and there is a good amount of info on authoring within the jquery docs.

Its worth noting that jquery is just javascript, so there is nothing special about a "jquery method".

Upvotes: 4

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