Browser extensions - DevTools extension

Today’s article will look at creating a Chrome dev tools extension.

It will be a basic setup. For now, that doesn’t do anything yet. It just shows you how we can inject something into the dev tools.

The result will look like this:

Creating a Chrome DevTools extension

To create the extension, create a new folder called devtools-extension, and open it up in your favorite editor.

Start by adding the brains of the operation, a file called manifest.json.

{
  "name": "DevTools extension",
  "version": "1.0",
  "manifest_version": 3,
  "devtools_page": "devtools.html"
}

This is all a basic dev tools extension needs. The most important part here is the devtools_page which defines which page it should inject.

Let’s add this basic base as well.

<!DOCTYPE html>
<html>
  <head>
    <script src="/devtools.js"></script>
  </head>
</html>

Yep, we’ll only use it to inject a JavaScript file. That file will, in return, be the source of adding the dev tools menu.

chrome.devtools.panels.create('DDT', null, '/panel.html', null);

The options in this panel create function are:

As we only want to display something we are good with the following, we can now go ahead and add this panel.html file.

<html>
  <head></head>
  <body>
    <h1>Basic devtools panel</h1>
  </body>
</html>

To add a dev tools extension, we can use the same process as we do for regular browser extensions.

And once done, head over to any random website, and you should be able to see your extension in the extra tools now.

You can also find this project on GitHub.

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