Typescript library generation

The idea to create a typescript library it's based on some code from a project, we identified that it could be better to extract some files as libraries so it can be installed as dependency on some microservices, preventing code duplication and easy maintainance.

This is an example librar that could help you on a similar scenario as above.

Installation

Libraries are generated the same way as a Node project

npm init

Configuracion package.json

Add some building scripts

"scripts": {
    "build": "tsc",
    "build:check": "tsc --noEmit",
  },  
  "main": "lib/index.js",
  "types": "lib/index.d.ts",
  "files": [
    "lib/**/*"
  ]

Neccesary dependencies installation

Since we are writing a typescript library we would need to install some depenendencies:

Typescript

npm i typescript

Types/node

npm i @types/node

Generating out project as a TS project : tsconfig.json

tsc --init

Directives created by the previous command can be updated as desired, these directives will be used at compiling time were mostly of the we tell what kind of verifications do we need over our code.

{
  "compilerOptions": {
    "target": "es5",
    "module": "commonjs",
    "moduleResolution": "node",
    "esModuleInterop": true,
    "resolveJsonModule": true,
    "lib": ["es6", "es2015"],
    "types": ["node"],
    "declaration": true,
    "outDir": "lib",
    "rootDir": "src",
    "strict": true,
  },
  "exclude": [
    "lib",
    "node_modules",
    "src/**/*.spec.ts"
  ],
  "include": [
    "src"
  ]
}
Doubts about tsconfig.json directives? => https://www.typescriptlang.org/tsconfig

Usage

export function helloSpace(spaceName:string) {
    console.log(`Hello space ${spaceName}`);
}

Type to compile out new library

npm run build

Previous commando will generate a new folder /lib were it is going to host some autogenerated .js and .d.ts files, were these types file are going to be neccesary for our TS project.

Working on testing our library on a local environment over other project

npm link

After running the above command over our library root folder, it will be available globally & locally to be consumed as a dependency on any of our local project just before publishing it to NPM.

In order for the library to be used on any of our local project, just run the below command

npm link library-name

This way the library will be included inside our node_modules folder to start using it.