How to Test TypeScript 7.1 Beta in a Vue Project Without Breaking Your Editor

A practical guide to testing TypeScript 7.1 beta and content mappers in a Vue project, while keeping TypeScript 6 handy in your editor.

Software engineering

Microsoft has released TypeScript 7.1 beta, the first update to the native compiler written in Go that arrived with version 7.0 in July. What's important for tool builders is that a programmatic compiler API is back, now split into separate entry points.

We've outlined the steps to calmly test it in a Vue project, which is where it makes the most difference. The idea is to measure before deciding and not touch the team's workflow until the ecosystem tools stabilize.

Terminal showing a type check of a frontend project with the total execution time — Measuring check time before and after is the best way to justify the migration.

What you need

A project with TypeScript and, ideally, .vue or .svelte components to leverage content mappers.
A separate branch or a test CI environment, to avoid mixing the beta with your daily workflow.
A reference figure: how long your type checking currently takes with the current tool.
A willingness to keep TypeScript 6 in your editor until Vue and Svelte tools have a stable version based on 7.1.

A preliminary note: the InfoQ chronicle itself reminds us that the beta arrived two weeks late and that the release candidate and stable versions are tentatively set for late November, according to the iteration plan. Treat it as a test, not a definitive migration.

Steps for testing

Note your current type checking time and save it as a baseline.
Create a test branch and install TypeScript 7.1 beta only on that branch.
If you use Vue, review the Vue Language Tools porting work, which already relies on content mappers and replaces the vue-tsc binary.
Run the check with the new compiler and compare it to your baseline.
Keep TypeScript 6 in your editor and 7.1 in CI until your framework releases stable tools.
Document any failures and notify the TypeScript team if you miss any API features.

# Install the beta only on the test branch
npm install --save-dev typescript@beta

# Check the installed version
npx tsc --version

What to expect from the results

In a documented migration of the Directus administration app, with 581 Vue components and 882 TypeScript files, the check went from 14.19 to 3.10 seconds. That's a 4.6x improvement over vue-tsc 3.

Don't expect the same everywhere. The MUI documentation benchmark dropped from 22.2 to 11.9 seconds with approximately half the memory, and in very large codebases like VS Code, the gain is around 1.2x. An independent test with NestJS measured 2.76 seconds in the beta versus 4.95 in 7.0.

Bar chart comparing type checking times between the old and native compilers — Improvements vary depending on the project size and nature.

Warnings to be aware of

There's an open issue: in a certain editor workflow, saving the configuration file that monitors a mapper can leave types outdated until the language server is restarted. Additionally, a mapper runs as a separate process and only if you activate it, so the team recommends treating it like any build plugin and checking its origin.

If you're coming from TypeScript 5, the advice is to go through 6 first and then to 7. And if you use Vue, Svelte, or Angular, keep a dual installation of TypeScript 6 and 7 until their tools release a version based on 7.1. The conversation on Hacker News shows that other type checkers are already being benchmarked against this beta.

Tip Save your baseline time and repeat the measurement several times before comparing: the first startup is usually slower than subsequent ones. If the numbers don't improve much in your project, don't force the migration yet.

Original source: infoq.com

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