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Learnings: Typescript: Configuring Language

Table Of Contents

Configuring Language

Ways of configuring:

  • tsconfig.json
  • compile time parameters passed to tsc
  • triple-slash directives: top of the file embed XML inside Javascript comments? But if you're doing this you're already in the weird...

... but apparently the triple-slash directives aren't supported by everything? A bit confused here...

And the CLI

running individual files through the compiler (playground style)

Running a single file through tsc will NOT pick up the options specified in tsconfig.json.

This makes the following use cases pretty annoying:

  • override a project's entrypoint with your own, for experimentation purposes
  • have a series of typescript files in a directory to show different aspects of the language
  • you are a beginning developer, or testing something out, and don't want to set up the entire project directory structure with proper entrypoint

a (bad) solution

I solved this by adding commands for my playground in my package.json's script section and manually setting the compile options I would have set in the tsconfig.json file as command line parameters.

This obviously doesn't work very well (at all) from a DRY perspective, but my other option (adding to the #! line and treating the .ts files as shell scripts) ALSO was no good (especially since I may be running the scripts on Windows).

making a bad solution slightly not so bad

Because npm scripts, if called with parameters, pass those parameters on to the command called - even if that's another npm command, we can abuse the system like so:

  "scripts": {
    "simple": "npm run basetsc -- --strict simple.ts",
    "record": "npm run basetsc -- --strict record.ts",
    "record-not-strict": "npm run basetsc record.ts",
    "basetsc": "tsc --outDir build --target es2017 --noUnusedLocals --noUnusedParameters --noImplicitReturns"
  }

simple.ts, record.ts etc are our scripts we want to play with.

You need to use -- so that npm doesn't swallow the arguments, but passes them along to the command.