How VS Code’s JavaScript/TypeScript Modernizer Automates Legacy Project Upgrades

Microsoft has quietly added a new feature to VS Code called JavaScript/TypeScript Modernizer , which leverages GitHub Copilot to help developers automatically modernize outdated JavaScript or TypeScript projects.

What the Modernizer does

The Modernizer is an AI‑driven project modernization tool bundled in the GitHub Copilot App Modernization extension. It performs three main actions:

Analyze your project : reads package.json to identify old dependencies and the size of version gaps.

Generate an upgrade plan : lists which packages need updating, the target versions, and any required code modifications.

Execute the upgrade automatically : updates package.json, reinstalls dependencies, and applies code changes.

Getting started

To use the Modernizer you only need to:

Install a Node.js environment.

Install VS Code, add the Copilot extension, and sign in to GitHub.

Install the GitHub Copilot app modernization extension.

Enable the experimental setting by adding the following line to your VS Code settings:

"appmod.experimental.task.typescript.upgrade": true

After restarting VS Code, a “Modernization” entry appears in the sidebar. Clicking Upgrade npm Packages triggers Copilot Chat to read the project, propose upgrades, confirm the plan, run installations, and even fix code errors caused by version changes.

Why it matters

This tool shifts Copilot from a code‑completion assistant to a maintenance‑level productivity aid, addressing the common pain of dependency upgrades that often cause cascading code changes. For front‑end ecosystems with rapid dependency turnover and frequent breaking changes, the Modernizer can act as an “annual health check‑up + auto‑upgrade assistant,” potentially cutting upgrade effort by more than half.

In summary, the Modernizer demonstrates Microsoft’s commitment to treating legacy project modernization as a solvable problem rather than a manual, error‑prone chore.