TypeScript 6.0 has reached release candidate stage as of March 6, with general availability planned for March 17. This is the last TypeScript version built on the JavaScript codebase — 7.0 will ship a Go-based compiler with dramatically faster performance — so 6.0 is essentially a bridge release, cleaning up defaults and deprecating legacy options before the big transition.
<h2>New features</h2>
Better type inference for this-less functions. Generic calls involving function expressions now get improved type inference, particularly in generic JSX expressions. This aligns behavior with what TypeScript 7.0 will do.
Subpath imports with <code>#/</code>. You can now use subpath imports starting with <code>#/</code>, which maps to Node.js’s package <code>imports</code> field.
<code>--moduleResolution bundler</code> + <code>--module commonjs</code>. These two options can now be combined, which wasn’t previously allowed.
New compilation targets and lib support. <code>es2025</code> is now a valid <code>--target</code> and <code>--lib</code> value.
Built-in Temporal API types. The DOM types now include the Temporal API from the latest web standards, along with <code>RegExp.escape</code> from the ES2025 proposal and <code>Map.getOrInsert</code> methods.
Consolidated DOM iterable types. The <code>dom.iterable</code> type definitions have been merged into <code>dom</code>, so you no longer need to reference them separately.
<code>--stableTypeOrdering</code> flag. A new diagnostic flag to help identify differences between 6.0 and 7.0 output.
<h2>Breaking changes</h2>
This is where 6.0 gets interesting — and potentially painful for existing projects. Several defaults have changed:
<ul>
<li><code>strict</code> is now enabled by default. If you weren’t already using strict mode, you will be.</li>
<li><code>module</code> defaults to <code>esnext</code> instead of <code>commonjs</code>.</li>
<li><code>target</code> defaults to <code>es2025</code> instead of <code>es3</code>.</li>
<li><code>types</code> defaults to <code>[]</code> (empty array) rather than auto-including all <code>@types</code> packages.</li>
<li><code>rootDir</code> defaults to the directory containing <code>tsconfig.json</code> rather than the longest common path of input files.</li>
</ul>
<h2>Deprecations</h2>
A long list of legacy options are now deprecated:
<ul>
<li><code>--target es5</code></li>
<li><code>--moduleResolution node</code> and <code>--moduleResolution classic</code></li>
<li>AMD, UMD, and SystemJS module formats</li>
<li><code>baseUrl</code></li>
<li><code>outFile</code></li>
<li><code>esModuleInterop false</code></li>
<li>Legacy module namespace syntax</li>
<li>Import assertion syntax (the <code>assert</code> keyword) is deprecated in both static imports and dynamic <code>import()</code> calls — use <code>with</code> instead.</li>
</ul>
If your project relies on any of these, 6.0 is a good time to migrate before 7.0 arrives and potentially removes them entirely.

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TypeScript 6.0 has reached release candidate stage (RC March 6, GA March 17). As the last TypeScript version built on JavaScript before the Go-based compiler arrives in 7.0, this release focuses on cleaning up defaults and deprecating legacy options. Key new features include improved type inference for this-less functions, subpath imports with `#/`, built-in Temporal API types, and an `es2025` compilation target. Breaking changes include `strict` now being enabled by default, `module` defaulting to `esnext`, `target` defaulting to `es2025`, and `types` defaulting to an empty array. A long list of legacy options are deprecated including `--target es5`, AMD/UMD/SystemJS module formats, `baseUrl`, `outFile`, and import assertion syntax.

TypeScript 6.0 RC: what's new and what's breaking