Hack the Editor: Craft Your Custom VS Code Extension Like a Pro 🚀

# Install global dependencies
npm install -g yo generator-code vsce
# OR with yarn
yarn global add yo generator-code vsce

yo code

my-first-extension/
├── .vscode/           # debug configurations
├── src/               # TypeScript source
│   └── extension.ts   # activation & commands
├── package.json       # manifest & contributions
├── tsconfig.json      # compile options
├── README.md          # your docs
├── .github/           # (if you choose CI)
└── test/              # Mocha tests

{
  "name": "my-first-extension",
  "displayName": "My First Extension",
  "description": "Says hello, shows TreeView, and Webview!",
  "version": "0.0.1",
  "engines": { "vscode": "^1.60.0" },
  "activationEvents": [
    "onCommand:extension.sayHello",
    "onView:myTreeView"
  ],
  "main": "./out/extension.js",
  "contributes": {
    "commands": [
      { "command": "extension.sayHello", "title": "Hello World" }
    ],
    "keybindings": [
      {
        "command": "extension.sayHello",
        "key": "ctrl+alt+h",
        "when": "editorTextFocus"
      }
    ],
    "views": {
      "explorer": [
        { "id": "myTreeView", "name": "My Custom View" }
      ]
    },
    "configuration": {
      "type": "object",
      "properties": {
        "myExtension.showWelcome": {
          "type": "boolean",
          "default": true,
          "description": "Show welcome message on activation"
        }
      }
    }
  }
}

import * as vscode from 'vscode';
import { MyTreeDataProvider } from './treeProvider';
import { createWebviewPanel } from './webview';

export function activate(context: vscode.ExtensionContext) {
  const config = vscode.workspace.getConfiguration('myExtension');
  if (config.get('showWelcome')) {
    vscode.window.showInformationMessage('Welcome to My First Extension! 🌟');
  }

  // Hello Command
  const hello = vscode.commands.registerCommand('extension.sayHello', () => {
    vscode.window.showInformationMessage('Hello, VS Code Extension!', '🎉 Celebrate', '📖 Docs')
      .then(selection => {
        if (selection === '📖 Docs') {
          vscode.env.openExternal(vscode.Uri.parse('https://code.visualstudio.com/api'));
        }
      });
  });

  // TreeView
  const treeDataProvider = new MyTreeDataProvider();
  vscode.window.createTreeView('myTreeView', { treeDataProvider });

  // Webview
  const webviewCmd = vscode.commands.registerCommand('extension.showWebview', () => {
    createWebviewPanel(context);
  });

  context.subscriptions.push(hello, webviewCmd);
}

export function deactivate() {}

import * as vscode from 'vscode';

export class MyTreeDataProvider implements vscode.TreeDataProvider<MyTreeItem> {
  private _onDidChange = new vscode.EventEmitter<MyTreeItem | void>();
  readonly onDidChangeTreeData = this._onDidChange.event;

  getChildren(): MyTreeItem[] {
    return [
      new MyTreeItem('Item One'),
      new MyTreeItem('Item Two')
    ];
  }

  getTreeItem(element: MyTreeItem): vscode.TreeItem {
    return element;
  }
}

class MyTreeItem extends vscode.TreeItem {
  constructor(label: string) {
    super(label);
    this.tooltip = `Tooltip for ${label}`;
    this.command = {
      command: 'extension.sayHello',
      title: 'Say Hello',
      arguments: []
    };
  }
}

import * as vscode from 'vscode';

export function createWebviewPanel(context: vscode.ExtensionContext) {
  const panel = vscode.window.createWebviewPanel(
    'myWebview', 'My Webview', vscode.ViewColumn.One, { enableScripts: true }
  );

  panel.webview.html = getWebviewContent();
}

function getWebviewContent(): string {
  return `
    
    
    Webview
    
      Hello from Webview!
      Click me
      
        const vscode = acquireVsCodeApi();
        function sendMessage() {
          vscode.postMessage({ command: 'alert', text: 'Button clicked!' });
        }
      
    
    
  `;
}



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Add message listener in activate if needed.
  
  
  Step 4: Compile, Debug & Lint 🚦


Compile: npm run compile


Lint: Add ESLint (npm install -D eslint @typescript-eslint/parser @typescript-eslint/eslint-plugin)

Debug: Press F5. In the Extension Development Host:



Command Palette: Ctrl+Shift+P → Hello World


Explorer: Find My Custom View


Command Palette: Show Webview




  
  
  Step 5: Testing 🧪
Yeoman scaffold includes Mocha. In test\extension.test.ts:

import * as assert from 'assert';
import * as vscode from 'vscode';

describe('Extension Tests', () => {
  it('should activate extension', async () => {
    const ext = vscode.extensions.getExtension('your-publisher.my-first-extension');
    await ext?.activate();
    assert.ok(ext?.isActive);
  });
});



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Run tests:

npm test



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Consider adding integration tests with @vscode/test-electron for UI flows.
  
  
  Step 6: Continuous Integration 🤖
Use GitHub Actions. Example .github/workflows/ci.yml:

name: CI
on: [push, pull_request]
jobs:
  build-and-test:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v2
      - uses: actions/setup-node@v2
        with: { 'node-version': '14' }
      - run: npm install
      - run: npm run compile
      - run: npm test
      - run: npm run lint



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This ensures every PR builds, compiles, and tests cleanly.
  
  
  Step 7: Package & Publish 📦


Package: vsce package → produces my-first-extension-0.0.1.vsix


Publish:


   vsce login 
   vsce publish



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Versioning: Follow Semantic Versioning to keep users happy.

  
  
  Pro Tips & Best Practices 🧙‍♂️


Lazy Activation: Only load heavy modules on demand.

Telemetry: Use vscode-extension-telemetry; always ask permission and respect GDPR.

Localization: Support multiple languages with package.nls.json.

Performance: Avoid blocking the main thread. Use background tasks if needed.

Documentation: Include a clear README, CHANGELOG, and demo GIFs.

Community: Respond to issues, tag PRs, and keep dependencies updated.

  
  
  Wrapping Up 🎁
You’ve built commands, views, rich web UIs, added testing, CI, and deployed to the Marketplace. But this is just the beginning:
Explore Debug Adapters and Language Servers
Create Custom Themes and Syntax Grammars

Integrate AI/ML for smarter coding assistance
Drop your extension links in the comments, share your learnings, and let’s push the boundaries of what VS Code can do—together. Happy coding! 💪Enjoyed this deep dive? Follow me for more tutorials and code adventures!