1. Remove the existing extension to avoid conflict. If you plan to be editing DesModder, I suggest opening a separate Chrome profile so that you still have the stable extension in your main profile when you need it.
2. Make sure you have git and npm installed.
3. Run git clone https://github.com/DesModder/DesModder to download the latest commit
4. Navigate to the directory, then run npm install to install dependencies
5. Run npm run build to build.
6. Load the unpacked extension in the dist/ folder through the directions at https://developer.chrome.com/docs/extensions/mv2/getstarted/#manifest (see "load unpacked")

First follow the instructions above in Setup.

1. Make sure you have the prettier and Typescript packages installed for your editor.
   • For Atom, these are prettier-atom and atom-typescript
   • VS Code comes bundled with Typescript support. Its Prettier extension is called "Prettier - Code Formatter," and I suggest the settings

     "editor.formatOnSave": true,
     "[typescript]": {
         "editor.defaultFormatter": "esbenp.prettier-vscode"
     }
     

2. Fork the DesModder repository to your GitHub account
3. Repeat the Setup directions with your fork repository instead of the main GitHub repository
4. Open your fork of the DesModder directory in your editor.
5. Open the file src/plugins.ts for this example.
6. Find the line that starts const _plugins = {, and add an extra newline after the opening brace. Prettier should automatically remove that unneeded newline on save.
7. Remove the .id from the next line. Typescript should tell you "A computed property name must be of type 'string', 'number', 'symbol', or 'any'."
8. If both of these worked, then you are ready to start development. Run npm run dev in the DesModder directory to start the development server. You should get no errors.
9. You should have loaded the unpacked extension based on the instructions in "Setup." Check that it works by opening https://desmos.com/calculator.
10. Back in src/plugins.ts, delete one of the lines declaring a plugin, for example delete [duplicateHotkey.id]: duplicateHotkey,
11. Reload the extension by opening the URL chrome://extensions and clicking the reload extension button
    • As far as I know, this is only necessary if the manifest or other files changed, so it is not strictly necessary here, but it is a good habit to get into
12. Refresh the Desmos page. The plugin should now be removed from the list.

In this section, we will create a plugin, which will simply change the displayed username in the top-right.

1. You should already have a fork of DesModder cloned to your computer

2. In the directory src/plugins, add a new directory called change-username and a file src/plugins/change-username/index.ts with the following contents:

   function getHeaderElement() {
     return document.querySelector(".header-account-name") as HTMLElement | null;
   }
   
   let oldName = "";
   
   function onEnable() {
     const headerElement = getHeaderElement();
     if (headerElement === null) {
       return;
     }
     const text = headerElement.innerText;
     if (text !== undefined) {
       oldName = text;
     }
     headerElement.innerText = "DesModder ♥";
   }
   
   function onDisable() {
     const headerElement = getHeaderElement();
     if (headerElement === null) {
       return;
     }
     headerElement.innerText = oldName;
   }
   
   export default {
     id: "change-username",
     name: "Change Username",
     description: 'Change your username to "DesModder"',
     onEnable: onEnable,
     onDisable: onDisable,
     enabledByDefault: false,
   } as const;

3. Load the plugin: In src/plugins/index.ts, add import changeUsername from "plugins/change-username/index" near the top and [changeUsername.id]: changeUsername, in _plugins near the bottom of the file.

   • after reloading the extension (assuming you're running npm run dev), a new plugin should appear in the list in desmos.com/calculator.

4. Commit the changes to your fork

   • git add .
   • git commit -m "🎉 Add Plugin: Change Username"
   • git push

5. For an actual plugin, you would do some more testing and eventually open a pull request on the repository.

I follow gitmoji.dev for commit emoji to add a bit of fun to committing (and of course it groups similar commits together, making it easier to understand what they do). There's even a VS code extension for it (vtrois.gitmoji-vscode).