esrun

esrun is a "work out of the box" library to execute Typescript (as well as modern Javascript with decorators and stuff) without having to use a bundler. This is useful for quick demonstrations or when launching your tests written in Typescript.

This library is a thin wrapper around esbuild which compiles Typescript almost instantly.

The harder work to run typescript is to deal with dependencies. For example, you may need to import other Typescript files, but also libraries written in Javascript and using either the CJS or the ESM format. All these use cases should be considered.

esrun is able to handle all the annoying stuff and make things work as you would expect.

Usage

Global installation

Install the library globally with your favorite package manager:

npm i -g @digitak/esrun

Then you can execute any Typescript file in the same way Node would execute a Javascript file:

esrun foo.ts

You can pass arguments like any process:

esrun foo.ts --option=bar --verbose -S

All file dependencies will be bundled and executed as well.

External module dependencies won't be bundled, it's up to the node engine to resolve dependencies.

Local installation

Install the library locally with your favorite package manager.

npm i -D @digitak/esrun

Then you can use it in your package.json scripts:

{
   "scripts": {
      "test": "esrun test"
   }
}

Running npm run test will run the first file that exists in the following list:

• /test.ts
• /test/index.ts
• /test/test.ts
• /test/main.ts
• /test.js
• /test/index.js
• /test/test.js
• /test/main.js

Importing a CJS module

If you import a CJS module, you may need to set the esModuleInterop flag in your tsconfig.json file:

{
    "compilerOptions": {
        "esModuleInterop": true
    }
}

This will allow you to write import ts from "typescript" instead of import * as ts from "typescript" - the latest syntax being not standard ESM.

Using a directory as an entry point

If the given entry point is a directory, the following actions will be executed in order to find the right entry file:

• check if a package.json file exists with a main field. The entry file will be the value of the main field, relative to the package.json directory.
• check if an index.ts file exists in the given directory.
• check if an eponym file exists in the given directory.
• check if an eponym file with the .ts extension exists in the given directory.
• check if a main.ts file exists in the given directory.
• check if a index.js file exists in the given directory.
• check if an eponym file with the .js extension exists in the given directory.
• check if a main.js file exists in the given directory.

API

The library exports a single function that you can use to programmatically execute a Typescript file.

import esrun from '@digitak/esrun'

esrun(filePath: string, argv: string[]): unknown