<p>TypeScript 6.0 is out, and it’s a transitional release - the last version built on the JavaScript codebase before the Go-native TypeScript 7.0 takes over. If you’re upgrading, expect some real breaking changes alongside the new features.</p>
<h2>What’s new</h2>
<p><strong>Better type inference for this-less functions</strong> is one of the headline improvements, along with support for subpath imports starting with <code>#/</code>. You can now combine <code>--moduleResolution bundler</code> with <code>--module commonjs</code>, which wasn’t possible before.</p>
<p>On the standard library side, 6.0 adds types for several TC39 Stage 4 proposals that are either already in engines or landing soon:</p>
<ul>
<li><strong>Temporal API</strong> - the long-awaited replacement for <code>Date</code></li>
<li><strong>Map.getOrInsert / Map.getOrInsertComputed</strong> - upsert methods for Map</li>
<li><strong>RegExp.escape</strong> - built-in regex escaping</li>
</ul>
<p>The <code>es2025</code> target and lib are now supported, and there’s a new <code>--stableTypeOrdering</code> flag specifically to help with the 6.0-to-7.0 migration.</p>
<h2>Breaking default changes</h2>
<p>This is where most people will feel the friction. Several tsconfig defaults have changed:</p>
<ul>
<li><code>strict</code> is now <code>true</code> by default</li>
<li><code>module</code> defaults to <code>esnext</code></li>
<li><code>target</code> defaults to <code>es2025</code></li>
<li><code>types</code> defaults to <code>[]</code> (empty) - this alone can cut build times by up to 50% by stopping TypeScript from automatically pulling in every <code>@types/*</code> package in your node_modules</li>
<li><code>rootDir</code> defaults to the directory containing your tsconfig</li>
</ul>
<p>If your project relied on the old defaults, you’ll need to explicitly set these values to keep existing behavior.</p>
<h2>Deprecations and removals</h2>
<p>TypeScript 6.0 is clearing out a lot of legacy options before 7.0 arrives:</p>
<ul>
<li><code>--moduleResolution node</code> is deprecated (use <code>node16</code>, <code>nodenext</code>, or <code>bundler</code>)</li>
<li><code>--baseUrl</code> is deprecated</li>
<li><code>--outFile</code> is deprecated</li>
<li>AMD, UMD, and SystemJS module targets are deprecated</li>
<li><code>target: es5</code> is deprecated</li>
<li>Module namespaces are deprecated</li>
</ul>
<p>These aren’t all hard removals yet, but the direction is clear.</p>
<h2>TypeScript 7.0 is close</h2>
<p>The Go-native compiler is already available as a preview in VS Code and on npm. A full release is expected within a few months. TypeScript 6.0 exists largely to smooth that transition - the new defaults and deprecations are meant to get codebases into a state where moving to 7.0 is less painful.</p>
<p>If you haven’t looked at your tsconfig in a while, now is a good time.</p>


Collections

TypeScript 6.0 is a transitional release bridging the current JavaScript-based compiler and the upcoming Go-native TypeScript 7.0. Key additions include better type inference for this-less functions, subpath imports with `#/`, support for combining `--moduleResolution bundler` with `--module commonjs`, and new standard library types for TC39 Stage 4 proposals like the Temporal API, Map.getOrInsert, and RegExp.escape. Several tsconfig defaults have changed — `strict` is now true by default, `module` defaults to `esnext`, `target` to `es2025`, and `types` to an empty array (which can cut build times by up to 50%). Legacy options including `--moduleResolution node`, `--baseUrl`, `--outFile`, AMD/UMD/SystemJS targets, and `target: es5` are deprecated. The Go-native TypeScript 7.0 compiler is already available as a preview and expected within months.

TypeScript 6.0 release notes: what changed and what's deprecated before 7.0