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by Simon Bisson

Contributing Writer

Revving up Microsoft’s 10x faster TypeScript 7

analysis

Jul 9, 20268 mins

Build type-safe JavaScript applications in less time with Microsoft’s native port of TypeScript built with Go.

Credit: Steve Mann / Shutterstock

It has been a year or so since Microsoft announced its plans to move TypeScript to a new, native runtime based on the Go language. Those first releases were unfinished (you had to compile them yourself) but showed promise, getting close to the expected 10x speed-up. That year has been one of steady progress, with Microsoft recently announcing the delivery of a release candidate build.

This release candidate is ready for use. It installs from npm like previous versions, and like earlier builds it works in much the same way as previous versions of TypeScript, checking types in your code, compiling it to run on ECMAScript-compliant JavaScript engines, and running just about anywhere. In addition, a native preview of the TypeScript language server for Visual Studio Code is available to help you write new TypeScript code and guide you through updating existing applications to the new language features.

All you need to do is enable the TypeScript 7 extension through the Visual Studio command palette and start coding. There&rsquo;s a lot of work going on to get the new tooling ready for the final release of TypeScript 7, and new versions of the language server are being released almost daily. It&rsquo;s certainly popular, too, with nearly half a million downloads at the time of writing.

What makes TypeScript 7 so much faster?

So how is this new TypeScript so much faster? Key to the improvements is a shift to a new native compiler built in Go. This has allowed the team to change how it operates, adding parallelization where possible. In some cases, this isn&rsquo;t easy, such as when type checking large codebases split across many files.

Here TypeScript spawns a small number of checker workers that run across your codebase. They work independently, so can duplicate the work — though the output will be the same. You can choose your own number of checkers, but the more you use, the more memory and CPU will be required.

Large monorepos with many projects require a similar approach with independent builder workers. You&rsquo;ll need to balance this with the number of checkers in use, as this can cause significant resource issues.

There are some significant language and configuration changes from TypeScript 5 (TypeScript 6 has the same changes, which makes it a useful tool for experimenting with migrations). It&rsquo;s well worth reading the release candidate documentation to understand how these will affect your code, as well as using the TypeScript 7 extension for Visual Studio Code to identify where you need to make changes.

Working with users to build language tools

One important aspect to the development of TypeScript 7 has been collaboration with existing users of the language and its tooling, as well as using the existing suite of TypeScript test tools that have been used to evaluate other versions. As this update is primarily a port of existing code, rather than a bottom-up rewrite, the underlying language semantics and structure are the same as those used in the original JavaScript codebase, ensuring that code will quickly port from old to new versions.

A major internal collaborator was the Visual Studio Code team, who have been using TypeScript to develop the familiar cross-platform development tool. It&rsquo;s an important partnership between tool and language, as VS Code is a key TypeScript development tool, hosting TypeScript&rsquo;s language server and using its compiler to provide debugging and code completion features.

The VS Code team published a long blog post detailing how it has been working with the Go-based TypeScript. The team is both helping to develop the language and beginning the process of moving its codebase to the newer, faster, native platform.

How the VS Code team migrated is a useful case study, one that can help you move your TypeScript development more efficiently and with minimal risk. The team began working with extensions, using daily builds of TypeScript to ensure that bugs and issues could be reported as they occurred and would only have a limited impact as fixes could be rolled out quickly. At the same time, the VS Code team began using a preview version of the TypeScript 7 extension for VS Code, which was being built around the new compiler in parallel with its development.

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