A plug-in is piece of code written in a standard JavaScript file. These files provide useful jQuery methods which can be used along with jQuery library methods.
There are plenty of jQuery plug-in available which you can download from repository link at https://jquery.com/plugins.
How to use Plugins
To make a plug-in’s methods available to us, we include plug-in file very similar to jQuery library file in the <head> of the document.
We must ensure that it appears after the main jQuery source file, and before our custom JavaScript code.
Following example shows how to include jquery.plug-in.js plugin −
<html><head><title>The jQuery Example</title><script type ="text/javascript"src ="https://www.tutorialspoint.com/jquery/jquery-3.6.0.js"></script><script src ="jquery.plug-in.js" type ="text/javascript"></script><script src ="custom.js" type ="text/javascript"></script><script type ="text/javascript" language ="javascript">$(document).ready(function(){.......your custom code.....});</script></head><body>.............................</body></html></pre>How to develop a Plug-in
This is very simple to write your own plug-in. Following is the syntax to create a a method −
jQuery.fn.methodName = methodDefinition;Here methodNameM is the name of new method and methodDefinition is actual method definition.
The guideline recommended by the jQuery team is as follows −
- Any methods or functions you attach must have a semicolon (;) at the end.
- Your method must return the jQuery object, unless explicity noted otherwise.
- You should use this.each to iterate over the current set of matched elements - it produces clean and compatible code that way.
- Prefix the filename with jquery, follow that with the name of the plugin and conclude with .js.
- Always attach the plugin to jQuery directly instead of $, so users can use a custom alias via noConflict() method.
For example, if we write a plugin that we want to name debug, our JavaScript filename for this plugin is −
jquery.debug.js
The use of the jquery. prefix eliminates any possible name collisions with files intended for use with other libraries.
Example
Following is a small plug-in to have warning method for debugging purpose. Keep this code in jquery.debug.js file −
jQuery.fn.warning=function(){returnthis.each(function(){alert('Tag Name:"'+$(this).prop("tagName")+'".');});};
Here is the example showing usage of warning() method. Assuming we put jquery.debug.js file in same directory of html page.
<html><head><title>The jQuery Example</title><script type = "text/javascript"src = "https://www.tutorialspoint.com/jquery/jquery-3.6.0.js"></script><script src = "jquery.debug.js" type = "text/javascript"></script><script type = "text/javascript" language = "javascript"> $(document).ready(function() { $("div").warning(); $("p").warning(); }); </script></head><body><p>This is paragraph</p><div>This is division</div></body></html></pre>This would alert you with following result −
This is paragraph This is division
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