Environment Setup

Reference: https://www.typescriptlang.org/docs/handbook/tsconfig-json.html

• target (read this):
  • specify what language features are available.
  • use highest possible version (allow advanced language features such as await...), but
  • depend on which platform to support (check this)
    • NodeJS
    • Electron (Javascript desktop application)
    • Browsers
  • determines default value of many other options
  • "ES3" (default), "ES5", "ES6"/"ES2015", "ES2016", "ES2017" or "ESNext".
• lib:
  • specify which libraries (in addition to supported by 'target') are available
  • if not specified a default list according to target is used
• module:
  • Specify module code generation
  • CommonJS - generates 'require...' to use with node
  • ES6 - 'import' style
• moduleResolution (see this):
  • Node - node type resolution

Example

{

    "compilerOptions": {

        "strict": true,

        "outDir": "build",

        // "allowJs": true, // cannot use together with 'declaration'

        "target": "es5",

        "module": "commonjs",

        "lib": [

            "es5",

            "es2015.promise"

        ],

        "sourceMap": true,

        "declaration": true,

    },

    "include": [

        "**/*.ts"

    ],

    "exclude": [

        "node_modules",

        "**/*.spec.ts",

        "build"  // exclude out dir when declaration is put

    ]    

}

• https://stackoverflow.com/questions/42088007/is-there-source-map-support-for-typescript-in-node-nodemon

• Use a starter https://github.com/bitjson/typescript-starter
  • A feature rich one
    • includes everything, build, tsline, prettier, test, debugging with VS Code, all included
    • uses 'ava' for testing, test case can be debugged with VS Code "Debug Spec" configuration, very convenient
  • WARNING: 'npm run all' includes 'npm run reset' which do 'git reset --hard', that resets all changes and deletes untracked files!!!!!

Packaging

To package a module for both Javascript & typescript use, enable "declaration" in compiling (tsconfig.json). Then use "main" and "types" in package.json to point to Javascript entry and Typescript declaration

   ...

   "description": "A nice greeter",

   "main": "lib/index.js",

   "types": "lib/index.d.ts",

   ...