What is a JQuery plugin and how to write it?

jQuery plugin is a piece of code that is built on top of the jQuery library to provide additional functionality. These plugins are assigned under the jQuery namespace or added to existing jQuery elements or objects. Writing a jQuery plugin allows you to extend jQuery’s prototype object, organizing your code and enabling you to write reusable code.

Here is a basic example of how to write a jQuery plugin:

```
(function($){ $.fn.myPlugin = function(options) {

// Default settings var settings = $.extend({ color: “#556b2f”, backgroundColor: “white“ }, options ); // Apply CSS styles return this.css({ color: settings.color, backgroundColor: settings.backgroundColor }); } }(jQuery)); ```

This is a very basic plugin called “myPlugin” that changes the text color and background color of an element. Here’s how to use this plugin:

```
$(‘p’).myPlugin({color:“red”, backgroundColor:“black”});
```

This code selects all paragraphs (‘p’ elements) and applies the myPlugin to them, passing in an options object to override the default settings of the plugin.

Remember that, as a best practice, always wrap your plugins inside a self-invoking anonymous function to avoid any conflicts with other JavaScript libraries or plugins that might be using the same variable names. Remember to pass jQuery to the function as well, so that you can use $ inside the function safely.