http://www.queness.com/post/112/a-really-simple-jquery-plugin-tutorial
1. Introduction
Creating a jQuery Plugin is an advanced topic for a jQuery beginner. This month, I have been playing with jQuery intensively. Though I have learnt how to separate the javascript code from html document, I ain't satisfy yet. Whenever I look at my javascript file, it's messy. So, I have decided to go one step further - learn how to write a jQuery plugin to tidy up the javascript file.
This plugin is based on my previous tutorial - Navigation List menu + jQuery Animate Effect Tutorial . Last time, I wrote the script and chucked in all the code in the document.ready section, like this:
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$(document).ready(function()
{ $('ul#menu
li:even').addClass('even'); $('ul#menu
li a').mouseover(function()
{ $(this).animate(
{ paddingLeft:"20px"},
{ queue:false,
duration:500 }); }).mouseout(function()
{ $(this).animate(
{ paddingLeft:"0"},
{ queue:true,
duration:500 }); }).click(function()
{ $(this).animate(
{ fontSize:"20px"},
{ queue:false,
duration:500 }); }); }); |
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$(document).ready(function()
{ $(#menu).animateMenu({ padding:20 }) }); |
It looks much more better, and easier to reuse this script for another project.
2. Plugin Structure
jQuery website has provided a very detailed explanation in Plugins/Authoring page. However, I found it's hard to understand.
Alright, to make your life easier, I did some research online, the following snippet will be a good structure to write a plugin.
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//You
need an anonymous function to wrap around your function to avoid conflict(function($){ //Attach
this new method to jQuery $.fn.extend({ //This
is where you write your plugin's name pluginname:function()
{ //Iterate
over the current set of matched elements returnthis.each(function()
{ //code
to be inserted here }); } }); //pass
jQuery to the function, //So
that we will able to use any valid Javascript variable name //to
replace "$" SIGN. But, we'll stick to $ (I like dollar sign: ) ) })(jQuery); |
2. Plugin With Options
If you look at step one - Introduction, the "padding" value for this plugin is user configurable. It good to have some settings so that user able to chage it according to their own needs. Please make sure you specify the default values for each of the variables for good practise. Now, you'll need the following code:
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(function($){ $.fn.extend({ //pass
the options variable to the function pluginname:function(options)
{ //Set
the default values, use comma to separate the settings, example: vardefaults
= { padding:
20, mouseOverColor
: '#000000', mouseOutColor
: '#ffffff' } varoptions
= $.extend(defaults, options); returnthis.each(function()
{ varo
= options; //code
to be inserted here //you
can access the value like this alert(o.padding); }); } }); })(jQuery); |
3. The animateMenu Plugin
Now you have learnt the plugin structure. The following is the plugin I created based on my previous tutorial. I have successfull convert the standard jQuery script to a plugin that accepts 4 configurations:
- animatePadding : Set the padding value for the animate effect
- defaultPadding : Set the default padding value
- evenColor : Set the color this color if index value is even number
- oddColor : Set the color this color if index value is odd number
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(function($){ $.fn.extend({ //plugin
name - animatemenu animateMenu:function(options)
{ //Settings
list and the default values vardefaults
= { animatePadding:
60, defaultPadding:
10, evenColor:'#ccc', oddColor:'#eee' }; varoptions
= $.extend(defaults, options); returnthis.each(function()
{ varo
=options; //Assign
current element to variable, in this case is UL element varobj
= $(this); //Get
all LI in the UL varitems
= $("li",
obj); //Change
the color according to odd and even rows $("li:even",
obj).css('background-color',
o.evenColor); $("li:odd",
obj).css('background-color',
o.oddColor); //Attach
mouseover and mouseout event to the LI items.mouseover(function()
{ $(this).animate({paddingLeft:
o.animatePadding}, 300); }).mouseout(function()
{ $(this).animate({paddingLeft:
o.defaultPadding}, 300); }); }); } });})(jQuery); |
4. Full source code
You can save the plugin in a separated file (for example, jquery.animatemenu.js). In this tutorial, I put the script in the html document.
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<!DOCTYPE
html PUBLIC "-//W3C//DTD
XHTML 1.0 Transitional//EN" <head> <title></title> <script>(function($){ $.fn.extend({ //plugin
name - animatemenu animateMenu:function(options)
{ vardefaults
= { animatePadding:
60, defaultPadding:
10, evenColor:'#ccc', oddColor:'#eee', }; varoptions
= $.extend(defaults, options); returnthis.each(function()
{ varo
=options; varobj
= $(this); varitems
= $("li",
obj); $("li:even",
obj).css('background-color',
o.evenColor); $("li:odd",
obj).css('background-color',
o.oddColor); items.mouseover(function()
{ $(this).animate({paddingLeft:
o.animatePadding}, 300); }).mouseout(function()
{ $(this).animate({paddingLeft:
o.defaultPadding}, 300); }); }); } });})(jQuery); </script> <script
type="text/javascript"> $(document).ready(function()
{ $('#menu').animateMenu({animatePadding:
30, defaultPadding:10}); }); </script> <style> body
{font-family:arial;font-style:bold} a
{color:#666;
text-decoration:none} #menu
{list-style:none;width:160px;padding-left:10px;} #menu
li {margin:0;padding:5px;cursor:hand;cursor:pointer} </style></head> <body><ul
id="menu"> <li>Home</li> <li>Posts</li> <li>About</li> <li>Contact</li></ul></body></html> |
I hope this tutorial will give you a better understanding. It isn't too hard at all to create a jQuery plugin. I was reluctantly to learn at first, but now, I realized how simple it is.
I will be publishing another tutorial soon - How to create a simple Accordion jQuery Plugin. So, stay tuned.
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