Creating CLI app with Type Script

• Create a typescrpt project
• Onelines on each library used
• Install as cli app
• publish to npm
• test in a docker image
• source map and debugging ?

Create npm project

yarn init

Install libs

• typescript : typescript compiler ??

• @types/node : types for nodejs

• @types/ts-node : running typescript without compiling

  yarn add -D typescript @types/node ts-node
  

  These are all compile time libraries.At runtime, we will have a simple js.

Create ts-config.json

• This file indicates that it is a typescirpt project

• It has compiler options for typescript compiler.

• Create it as :

  {
    "compilerOptions": {
      "baseUrl": ".",
      "target": "ES2017",
      "module": "commonjs",
      "strict": true,
      "esModuleInterop": true,
      "rootDir": "src",   # Our ts files
      "outDir": "dist"    # Compiled js files
    }
  }

  Notice "outDir": "dist". Our compiled js files are created here.

Create and index.ts

console.log("Hello from index.ts");

Create script to compile and run index.ts in package.json

  "scripts": {
    "compile": "tsc ",
    "start": "node dist/index.js"
  },

yarn compile
yarn start
# output : 
# Hello from index.ts

Use ts-node to run without compiling in package.json

	"scripts": {
    "compile": "tsc ",
    "start": "node dist/index.js",
+   "dev": "ts-node src/index.ts"
  },

Create a bin (binary) to run for our program in package.json

  "bin": {
    "ts-cli-app": "dist/index.js"
  },

In index.ts, add directive to instruct shell on how to run this file :

#!/usr/bin/env node

Test by installing it on local machine

yarn link
ts-cli-app
# output : 
# Hello from index.ts

Publish to npm

# Publish to npm org.
yarn publish

# Test with a fresh install in a docker image
docker run node:14 npx ts-cli-app 

Refer:

• https://walrus.ai/blog/2019/11/typescript-cli/