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module-specifier-resolver

This tool transforms module specifier of TypeScript source code when it contains.
Because ECMAScript Modules(ESM) system doesn’t allow to abbreviate file extension, so this tool aim to follows the system.

use cases

  • You want to migrate your development enviroment like below.
    • From Node.js & TypeScript 4.7 ~ 4.9 to Node.js & TypeScript 5.0 ~
    • From Node.js & TypeScript to Deno & TypeScript in the near future

transform example

a file tree as follows

root
├── foo.ts
├── bar.ts
└── cool
    ├── index.ts
    └── cool.ts

before

  • foo.ts

    // If your TypeScript "compilerOptions" has set "moduleResolution": "nodenext", it will be like below.
// import { bar } from './bar.js'
import { bar } from './bar'
import { cool } from './cool'
console.log(bar)
console.log(cool)

  • bar.ts

    export const bar = 42

  • cool/index.ts

    export { cool } from './cool'

  • cool/cool.ts

    export const cool = 'this is cool'

after

  • foo.ts

    import { bar } from './bar.ts'
import { cool } from './cool/index.ts'
console.log(bar)
console.log(cool)

  • cool/index.ts

    export { cool } from './cool.ts'

limitation

  • Can’t resolve paths alias of TypeScript compiler options.
  • Can’t resolve import() syntax, commonly called dynamic import.
  • Plase be careful if your code have the text /* _PRESERVE_NEWLINE_ */ which will be replace newline, because of that keeps original newline before tsc compiler optimize it.
  • Can’t keep single quatation or duble quatation , semicolon and indatation of original source code.

tools

Please install Deno.

command

remote

  • dry run
    • deno run --unstable --allow-env --allow-read --allow-write https://deno.land/x/module_specifier_resolver@v1.0.14/bin.ts -b=./src -c=./tsconfig.json -d
  • transform
    • deno run --unstable --allow-env --allow-read --allow-write https://deno.land/x/module_specifier_resolver@v1.0.14/bin.ts -b=./src -c=./tsconfig.json -r

local

  • deno task run-dry
  • deno task run

arguments

key description type default
-b local of base directory string .
-c local of base tsconfig.json string ./tsconfig.json
-d dry run boolean false
-r enable repl interface boolean false

tips

After you ran bin.ts, you should run npx tsc --noEmit and your bundler’s build command due to check correctness of transformation by this tool.

  • tsconfig.json example
    {
  "compilerOptions": {
    "moduleResolution": "bundler",
    "allowImportingTsExtensions": true,
    "noEmit": true
  }
}

License