How to write a WordPress Plugin part 3 – Creating the WordPress Plugin

Creating the WordPress Plugin

Ok, you just created the Javascript/HTML/CSS code you want to use for your WordPress site on an HTML page. How the heck you get this into your WordPress page? Well, with the magic of plugins.

What are plugins?

Plugins are a file and directory structure used by WordPress to add code to your WordPress site. Here is an example of the directory structure .


The main file that tells WordPress plugin how to run is movetotop.php

The other directories and files are: – Markdown readme file.
assets – image files and fonts used by plugin. Fontawesome is used here.
css – Cascading Stylesheet used by plugin. The stylesheet totop.css lives here
js – JavaScript files used by plugin. The JavaScript totop.js file code is here.

Creating the plugin.

Chop it up.

First things first, we will “chop” up the HTML and JavaScript code and place it where it needs to go.

To make the file naming consistant with the plugin name, I renamed the custom.css file to totop.css and custom.js to totop.js. Otherwise, there is no change to the content of the files or code enclosed.

I also separated the fontawesome files into assets/fontawesome-5 directory so to better organize these assets.

Movetotop.php and how it’s organized.

The real magic of WordPress plugin is found in the movetotop.php file.

There are three sections found in a plugin file:

Header. This is commented header enclosed is /* */

add_action/add_filter – this tells WordPress to execute scripts to add the CSS/HTML/JavaScript files into the HTML generated by WordPress sent to the web browser.

Function(s). This is the scripts that injects the CSS, HTML or JavaScript files when called by add_action/add_filter.

Well, let’s go into how this file is created and what is used.

Header File

Header file contains the following:

Plugin Name:
Plugin URI:
Author URI:

This is self explanatory. Without this information, the plugin will not show up in the WordPress plugin dashboard.

The hook function

The hook functions add_action/add_filter – This adds the CSS/HTML and JavaScript file into WordPress hooks. Generally, hooks are the location of the content.

Here are the five hooks used by this plugin:


Basically, the format is:

(Location of content(hook), Function content to be applied).

There are MORE hooks than what we’re using here (over 1,000+ hooks, see this link for a comprehensive list) which do a variety of things. For this example we’re just sticking to the basic ones.


The function that injects the content inside the HTML.

Here is an example:

function AddMoveToTopCSS() {
<link rel=”stylesheet” href=”<?php echo $cssurl; ?>”>
<?php }

This function injects the css/totop.css file name and location and outputs it as a text HTML reference. This is then called by the hook function and injected in the location (hook) specified.

Wrap up.

That’s how you develop a basic WordPress plugin. We didn’t cover other stuff like an admin backend interface with configurable parameters. That we may do another time.

In the meantime, have a good day.






How to write a WordPress Plugin part 2 – Static HTML/CSS/JavaScript

When you write a WordPress plugin, you are essentially inserting HTML and JavaScript code into a webpage. The first thing you do is write a static HTML page with the effect you have in mind first.
While there are several kinds of plugins available for WordPress, we’ll only concern ourselves with adding a feature to the site as described above.

The first thing I did was fire up my favorite editor.
I used Visual Studio Code You can use any editor you wish such as Sublime, Brackets, Notepad++, Atom.
I like VS Code since it integrates EMMET, has built in IntelliSense, and supports several plugins that make it very useful.

If you follow the link, you can download the source files.

The first file I’d like you to look at is the index.htm file.
If you open it up in a web browser, you will see a bunch of lorem ipsum text. You scroll down the page, the “move-to-top” button will show up at the lower right hand corner of the web page. You press the button and the page will scroll to the top of the page.
Open up this index.htm file in the editor and I’d like you to notice the following:

<script type="text/javascript" src="./js/lib/jquery/jquery-1.10.2.js"></script>
<script type="text/javascript" src="./js/custom.js"></script>
<link rel="stylesheet" type="text/css" href="./css/fontawesome-all.css"/>
<link rel="stylesheet" type="text/css" href="./css/custom.css"/>

To make the button appear, we need the following:

JQuery – for the animation effects.

FontAwesome – for the up angles in the button.

custom.js – for the JavaScript code.

custom.css – for the styling of the button.

We also have the button itself with the FontAwesome fonts in the HTML.

<button onclick="topFunction()" id="toTop" title="Go to top"><i class="fas fa-angle-double-up fa-2x"></i></button> 

This code has to first work in a static HTML page before you make it work anywhere else.
I tweeked the code until it looked right and behaved as I expected it to here before making it work as a plugin in WordPress.

I won’t go into detail about how to write JavaScript or write CSS styling. You can examine the code and see how it works.

What I want you to notice is where the snippets of code are placed in the HTML. This is where the snippets need to be placed in the WordPress dynamically generated pages.

In this case, the code is in the header of the HTML and the body.

The next article will describe how to turn it into a WordPress plugin.


Writing a basic WordPress plugin (MoveToTop) part 1 – Basic overview

You may wonder how you go about modifying your WordPress site just adding a piece of JavaScript code.

Perhaps you are handy with writing some HTML, CSS, and JavaScript but you don’t know where to begin with converting it into a plugin for WordPress.

I will show you how you can do this with the MoveToTop example plugin that I have created and placed on GitHub.

You don’t have to write a whole blown out plugin if you just want to add a simple code snipped or tweak to your site, plus you can use it in ANY of your sites you need this snippet.

This plugin which I use on this site, creates a button on the lower right corner of the web page. When you click on it, it moves the web page to the top of the page (Get it…move to top…) You can customize it’s behavior and appearance by modifying the CSS and JavaScript code.

To get this magic to work, the first thing you need to do is to write a basic HTML page with the plugin in question. The script (totop.js) has to be working along with the HTML (found in movetotop.php), CSS (totop.css) appropriate libraries such as J QueryFont Awesome.

I wrote a static HTML page and made this page work first.

In the next article, I will show you how I developed the test code.