Reduce building types time by caching old types

[nvh95]

Issues

Emitting types takes a long time. it took twice as long as bundling

Features

• Reduce building types time by caching old types

Related tweets

• Problem: https://twitter.com/hung_dev/status/1538353502095028224
• Solution: https://twitter.com/nhducit/status/1538537067231477760 (idea of @nhducit)

Important notes

• Solution: Use incremental flag to cache last computation.
• Caveats:
  • incremental cannot be used in CLI => add tsconfig.types.json to emit types
  • If I run npm run build, it leads to this command is executed rimraf dist, which means cache will be cleared => incremental flag have no effect
    => solution: write custom scripts/clearBuildFolder.js script to keep .d.ts, tsconfig.types.tsbuildinfo and .npmignore
  • tsconfig.types.tsbuildinfo appear in dist folder, which will be shipped to npm registry
    • Try to ignore by adding dist/tsconfig.types.tsbuildinfo to .npmignore at root of project => The reason is we whitelist dist by field files in package.json. files have highest priority
      => I have to add tsconfig.types.tsbuildinfo to dist/.npmignore => npm ignore when publish to registry
    • dist folder is ignored by .gitignore => I have to temporary un-ignore dist folder to commit dist/.npmignore

Concerns

• I still have concerns about this strategy. It could be a serious issue if I accidentally mess up with the cache.
  => Possible solution:
• Opt-out caching when build latest version

Reference

https://github.com/microsoft/TypeScript/wiki/Performance#incremental-project-emit

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[nvh95]

@all-contributors please add @nhducit for idea

[allcontributors]

@nvh95

I've put up a pull request to add @nhducit! 🎉