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TypeScript 6 vs 7: The Native Compiler Bridge Release

TypeScript 6 vs 7 explained: version 6 is the JavaScript-based bridge that flags every option TypeScript 7 turns into a hard error.

· · 8 min read

Updated: August 8, 2026

Code editor displaying React source files

Quick Take

TypeScript 6 is the final JavaScript-based release and the bridge to TypeScript 7. It names every option 7 will delete and lets you defer the fix, so you clean them up on 6 before you run the Go compiler.

Run this yourself. One tsconfig, both compilers, four asserted outcomes, including the ignoreDeprecations escape hatch: typescript-7-deprecations/ in the Coding Dunia code-examples repo.

Quick take: TypeScript 6 is the last JavaScript-based release, and it exists to smooth your path to TypeScript 7 (Project Corsa). Every compiler option that disappears in 7 gets named in 6 first, as TS5107, with an ignoreDeprecations opt-out so your build can stay green while you work through the list. Upgrade to 6, clear the list, then bump to 7.

So what actually separates TypeScript 6 from TypeScript 7? The type system, nothing at all. Generics, conditional types, mapped types, strict-mode inference, all identical. The real split is the compiler underneath and how each version treats old settings. TS 6 runs on the same JavaScript engine that has shipped since 2012. TS 7 runs on a native Go rewrite that Microsoft clocks at 8x to 12x faster full builds. And the options TS 7 deletes outright? TS 6 still compiles them, but only after it has named each one and you have acknowledged the list. That gap is the entire point of the release. If you want the full Go-rewrite backstory, I keep it in the Project Corsa overview; this piece is about the 6-to-7 seam specifically.

Why does TypeScript 6 even exist?

TypeScript 6 is a bridge, not a destination. Microsoft split the upgrade into two hops on purpose. Version 6 is the final release built on the original JavaScript codebase, nicknamed Strada. It ships the same speed you're used to, the same type-checker, the same emit. What it adds is a wall of deprecation diagnostics. Anything TS 7 removes, ES5 output, AMD and UMD and SystemJS modules, the classic and node10 resolution modes, still compiles on 6, but every one of them is reported as TS5107 and the build stops until you either fix it or add "ignoreDeprecations": "6.0" to your tsconfig. Think of 6 as a linter you cannot ignore by accident. You still get to fix things on your own schedule, and with that one line the builds stay green while you do.

What Actually Differs Between TypeScript 6 and TypeScript 7?

Project Corsa is Microsoft's codename for the native Go rewrite of the TypeScript compiler that ships as TypeScript 7, replacing the JavaScript-based Strada codebase that has powered every release since 2012. Six dimensions separate the two versions in practice: the language the compiler itself is written in, raw build speed, how deprecated options are handled, which module formats still emit, whether strict mode defaults on, and the editor experience. Microsoft clocks the Go compiler at 8x to 12x faster full builds than the JavaScript one (our own tsgo speed benchmarks put that claim to the test on real repos), and that speedup is the headline reason teams want to move, but the deprecated-option handling is what actually determines how painful the move is. Here's the side by side, same language features, very different tolerance for legacy config.

DimensionTypeScript 6TypeScript 7
Compiler languageJavaScript (the Strada codebase)Go (Project Corsa)
Build speedSame as TS 5.x8x to 12x faster full builds
Deprecated optionsTS5107, deferrable with ignoreDeprecations: "6.0"TS5108, removed, no opt-out
Module outputES5, AMD, UMD, SystemJS still emitES5/AMD/UMD/SystemJS all removed
Default strictnessstrict is on by defaultstrict is on by default
Editor experienceJS-based language serviceNative Preview extension, near-instant

The row that matters most is the third one. On 6 a deprecated option costs you a diagnostic you can silence with one config line while you clean up. On 7 the option is gone and there is nothing to silence. Almost everything else in a real migration follows from that single difference. Both versions turn strict on when your tsconfig does not mention it, which surprises people upgrading from 5.x more than the removals do.

A dirt path in a forest splitting into two directions
Photo by Jens Lelie on Unsplash

How does the deprecation stage de-risk the jump?

Picture two teams. One goes 5.4 straight to 7.0. The other parks on 6 for a sprint. The first team runs the native compiler cold and gets a screen of errors with terse, Go-generated messages, no context, no "this used to be allowed." The second team saw the same problems weeks earlier as readable diagnostics that named the exact flag, the exact file and the version that drops it. Which afternoon would you rather have?

I lived the second path on a 40,000-line React app in June 2026. TS 6 named our moduleResolution: "node10" in a TS5107 and told me exactly which version drops it, and two packages still leaned on it. Small fix, ten minutes. When I later flipped that same repo to 7, the identical config would have thrown TS2307: Cannot find module across a dozen imports at once, the kind of error that sends you chasing the wrong cause for an hour. Catching it on 6, where the message names the option instead of the symptom, turned a cryptic 7 failure into a boring one-line edit. That is the value of the bridge, and it kills most of the risks that make the jump feel scary. It's also why I think skipping 6 is a false economy.

What's the deprecation triage workflow?

Deprecation triage is the process of working through a compiler's deprecation list one flagged option at a time until the build is clean, and TypeScript 6 is built specifically to make that process mechanical rather than guesswork. Three moves get you there, nothing clever:

  1. Install TypeScript 6 and print your effective, fully-resolved config.
  2. Run a no-emit check and fix every TS5107 it surfaces, not just the ones that look scary.
  3. Once tsc --noEmit is silent, bump the version to TypeScript 7 and re-check.

First, install 6 and print your effective config:

npm install -D typescript@6
npx tsc --showConfig

tsc --showConfig prints the fully resolved tsconfig, including inherited and default values you never wrote by hand. Read it for the options 7 kills.

Second, run a no-emit check and take every TS5107 seriously:

npx tsc --noEmit

Fix them in place. Swap target: "es5" for es2021 or newer. Move module off AMD or UMD onto esnext or nodenext. Replace moduleResolution: "node10" with "bundler" or "nodenext". Turn strict on now, because 7 defaults it on regardless.

Third, once tsc --noEmit is silent, bump the version and re-check:

{
  "devDependencies": {
    "typescript": "^7.0.0"
  }
}

A repo that clears its deprecation list on 6, with ignoreDeprecations removed again at the end, usually comes up green on 7 the very first run. Isn't that a nicer Friday than debugging a wall of Go errors you've never seen before? Want to skip the manual tsc --showConfig read-through? Paste your tsconfig.json and package.json into the TypeScript 7 Migration Readiness Checker and it flags the same removed options with a scored report and copy-ready fixes.

A single open path leading toward a warm sunset horizon
Photo by Karsten Wurth on Unsplash

Should you skip 6 and jump straight to 7?

Honestly? Only if your tsconfig is already spotless and you like living dangerously. For a greenfield project with strict on and modern module settings, go straight to 7, there's nothing for 6 to flag. For anything with history, the two-hop route is faster in wall-clock terms even with the extra step, because every problem shows up pre-labeled instead of raw. The exact command sequence, tool by tool, lives in the full migration guide. Do the boring thing here. Stop at 6, clear the list, then move.

  • TypeScript 7 hub - the full picture: orientation, the migration routes, the framework matrix, the benchmarks, and the readiness checker on one page
  • TypeScript strict mode guide - turn strict on during the 6 step, since TypeScript 7 defaults it on anyway
  • TypeScript 7.0 Is GA - the GA announcement covering what shipped in the release these two versions compare against
  • TypeScript 7 framework support - check whether your framework's tooling has caught up before you bump the version

Check Your Own tsconfig.json

Paste it below for an instant readiness score against everything TypeScript 7 removed or changed. Runs in your browser, nothing is uploaded.

Need to check package.json too, or want the full breakdown? Use the full TypeScript 7 Migration Readiness Checker.

Frequently Asked Questions

Is TypeScript 6 a required step before TypeScript 7?
It isn't strictly required, but it's the safe path for any existing project. TypeScript 6 flags every option that TypeScript 7 removes as TS5107, naming the option and the version that drops it, and the ignoreDeprecations 6.0 setting keeps your build green while you work through the list. That lets you fix each one on your own schedule instead of hitting a wall of removals on 7.
What does TypeScript 6 do that TypeScript 7 doesn't?
TypeScript 6 still compiles the legacy settings that 7 deletes, like ES5 output and AMD or UMD modules, but only once you acknowledge them with ignoreDeprecations 6.0. Without that line it reports TS5107 and stops. TypeScript 7 reports TS5108, has removed the options outright, and offers no equivalent opt-out.
Can I jump straight from TypeScript 5.x to TypeScript 7?
You can, but you skip the layer that makes the move readable. Going straight to 7 surfaces every removed option at once as a terse TS5108 from the native Go compiler. Stopping at 6 first names each problem, points at the migration notes, and lets you defer it rather than fix it under pressure.
Does TypeScript 6 change the type system?
No. Generics, conditional types, mapped types, and strict-mode inference behave exactly as they did in TypeScript 5. What changes in 6 is the batch of deprecation diagnostics that preview what 7 removes, plus strict defaulting to on when your tsconfig says nothing about it.
How do I find the options TypeScript 7 will break?
Install TypeScript 6, run tsc --showConfig to print your fully resolved settings, then run tsc --noEmit and read the TS5107 list. Every flagged option is one that stops existing on TypeScript 7.