Add release dates to TypeScript version selector in playground

[Copilot]

The playground version selector now displays release dates alongside version numbers to provide context about when each TypeScript version was published.

Changes

Data Layer

• Enhanced downloadReleases.js to fetch release dates from npm registry and generate release_data.ts with version/date mappings
• Added ReleaseInfo interface with version: string and date: string | null (null for beta/RC without dates yet)
• Created SupportedReleaseVersions type for type-safe releaseInfo keys

Sandbox

• Export releaseInfo from sandbox to make date information available to playground

Playground

• Format version entries as "5.6.3 (Oct 8, 2024)" using toLocaleDateString('en-US')
• Gracefully handle missing dates by showing version only

Example

Version dropdown now shows:

Nightly
5.9.3 (Sep 30, 2025)
5.7.3 (Jan 8, 2025)
5.6.3 (Oct 8, 2024)
5.5.4 (Jul 22, 2024)
...

Regenerate with: pnpm run --filter=@typescript/sandbox bootstrap

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• playgroundcdn.typescriptlang.org
  • Triggering command: /usr/local/bin/node node script/downloadReleases.js nfig/composer/veinstall grep 2.5.3/node_modules/lmdb/node_modules/.bin/../../../../../node-gyp-build-optional-packages@5.0.3/node_modules/node-gyp-build-optional-packages/build-test.js on.*date ugins.ts /snap/bin/grep on.*date n /opt/pipx_bin/grep grep -l on.*date opy/en/Playground/Tooling/Mobile Support.ts p/bin/grep on.*date _files.ts grep grep (dns block)
  • Triggering command: /usr/local/bin/node node script/downloadReleases.js ules/.pnpm/rxjs@build ules/.pnpm/rxjs@--tsconfig ules�� ules/.pnpm/rxjs@6.6.7/node_modules/rxjs/fetch/index.js ules/.pnpm/rxjs@6.6.7/node_modules/rxjs/index.d.ts Website/node_modules/.pnpm/eslin/home/REDACTED/work/TypeScript-Website/TypeScript-Website/node_mod--porcelain Website/node_modnode Website/node_mod/home/REDACTED/work/TypeScript-Website/TypeScript-Website/packages/san�� Website/node_modules/.pnpm/eslin--noprofile Website/node_modules/.pnpm/eslin/home/REDACTED/work/TypeScript-Website/TypeScript-Website/node_modules/.pnpm/cssst/home/REDACTED/work/TypeScript-Website/TypeScript-Website/node_modules/.pnpm/ramda--norc Webs�� Website/node_modules/.pnpm/eslin/home/REDACTED/work/TypeScript-Website/TypeScript-Website/node_modbash Website/node_modules/.pnpm/rxjs@6.6.7/node_modules/rxjs/src/internal/observable/dom/ajax.ts Website/node_modules/.pnpm/rxjs@6.6.7/node_modules/rxjs/src/internal/observable/dom/WebSocketSub--noprofile Website/node_modbash Website/node_mod--norc Website/node_mod--noprofile Website/node_modules/.pnpm/rxjs@time (dns block)
• typescript-api.vercel.app
  • Triggering command: /usr/bin/curl curl -s REDACTED grep 2.5.2/node_modules/lmdb/node_modules/.bin/../../../../../node-gyp-build-optional-packages@5.0.3/node_modules/node-gyp-build-optional-packages/build-test.js on.*date opy/en/TypeScript/Primitives/Unknown and Never.ts ules/.pnpm/core-js@3.37.1/node_modules/core-js/node_modules/.bin/node on.*date c/copy/en/tsconf-e @18.3.1__flfdymwczvzjjewgfdgpfbffle/node_modules/gatsby/node_modules/.bin/node grep -l on.*date opy/en/4-4/New JS Features/Errors for High Confidence Errors.ts ules/.pnpm/sharp@0.28.1/node_modules/sharp/node_modules/.bin/getconf on.*date wJS.ts /opt/pipx_bin/grep grep (dns block)
• unpkg.com
  • Triggering command: /usr/local/bin/node node scripts/postinstall.js rgo/bin/grep grep -l on.*date ugins.ts ules/.bin/node on.*date n /home/REDACTED/.local/bin/grep grep -l on.*date opy/en/Playground/Tooling/Mobile Support.ts nfig/composer/vendor/bin/grep on.*date _files.ts n/node-gyp-build-optional-packages grep (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

Original prompt

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This section details on the original issue you should resolve

<issue_title>Add release dates to each release number in the playground</issue_title>
<issue_description>This was something that @RyanCavanaugh brought up as an idea for the playground version selector.</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Add release dates to each release number in the playground #3468

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[danthedaniel]

Copilot please use an as const array and derive ReleaseVersions using typeof supportedReleases[number].