Most of us You spend a lot of time inside a web browser. If you’re a Chrome, Firefox, or Edge user, you’ll know that these browsers come with a host of third-party extensions to augment the features already built into the software.
But what if you need some kind of specific extra functionality, some tool or feature that isn’t covered by existing add-ons? Then maybe it’s time to consider writing your own browser extension. It may seem daunting, but it’s not that hard to do once you learn how. And once you’ve created a custom extension, you can keep it for your own private use or make it public for anyone to use.
Some coding knowledge is required, so you’ll need to learn the basics of how web pages and scripts are written if you don’t already know them. If you’re a beginner, you can start small and work your way up. There are also plenty of useful resources on the web if you need them, from code libraries to online courses.
Begin
There are certain components that make up a browser extension. The first is the manifest, which takes the filename manifest.json and contains several pieces of metadata that identify the extension and what it does. The extension’s name is placed in the manifest, it describes what it does, and it specifies a default action that the extension performs.
Review the manifest file format Documentation provided by Google for Chrome. You can see some examples there, including a minimal manifest that only contains the basics. The manifest lists all the other files needed for the extension, which should be saved in the same folder you develop it in.
Some of the files that the manifest points to are icon files, which visually represent your extension in the browser. Users will look for your icon to see that your extension is running, and click the icon to access the extension’s settings or to disable it. You should create an icon that is at least 128×128 pixels, and icons of other sizes (as listed here) are recommended, so that the extension looks the same everywhere it appears in the browser, from the settings screen to the tab bar. If you don’t provide an icon, a generic one showing the first letter of the extension name will be used.
Then you have your scripts, which do the actual work of the extension and can come in a variety of forms: HTML (Hypertext Markup Language) for basic web design, CSS (Cascading Style Sheets) for more advanced styling and manipulation of objects on the web, and JavaScript to do the bulk of the programming tasks (assuming your extension does anything more than just load a page on the screen).
