[TypeScript] Initialize a TypeScript Node.js project

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TypeScript Node.js Project

TypeScript is a strongly typed programming language that builds on JavaScript, giving you better tooling at any scale.

Node.js® is a JavaScript runtime built on Chrome’s V8 JavaScript engine.

This article is about how to setup Typescript project from scratch.

Prerequisites

Create a node project using npm

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$ npm init -y

# Or yarn
# $ yarn init -y

Install Typescript dependencies

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$ npm i --save-dev typescript ts-node nodemon

Dependencies:

  • typescript is for Typescript language itself and compiling tool

  • ts-node is used to run Typescript without compiling

  • nodemon is used to run/restart node automatically when files changed

Initialize tsconfig.json

Creates a tsconfig.json in your project folder. This controls the strictness/settings in Typescript files

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$ npx tsc --init

Adjust tsconfig [optional]

Some basic settings in tsconfig.json that are recommended are:

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{
  "compilerOptions": {
      "experimentalDecorators": true,
      "forceConsistentCasingInFileNames": true,
      "module": "commonjs",
      "moduleResolution": "node",
      "noFallthroughCasesInSwitch": true,
      "noImplicitReturns": true,
      "outDir": "dist",
      "pretty": true,
      "sourceMap": true,
      "strict": true,
      "target": "es2016",
  },
  "files": [
      "index.ts"
  ]
}

Common Compiler Options:

  • experimentalDecorators true enables experimental support for decorators - https://github.com/tc39/proposal-decorators, which is in stage 2 of the TC39 standardization process.

  • forceConsistentCasingInFileNames true TypeScript will issue an error if a program tries to include a file by a casing different from the casing on disk.

  • module Sets commonjs as the module system for the program. See the Modules - https://www.typescriptlang.org/docs/handbook/modules.html reference page for more information. You very likely want “CommonJS” for node projects.

  • moduleResolution node specify TypeScript looks up a file from Node.js’ CommonJS implementation.

  • noFallthroughCasesInSwitch true report errors for fallthrough cases in switch statements.

  • noImplicitReturns true will check all code paths in a function to ensure they return a value.

  • outDir redirects output structure to the directory

  • pretty true stylize errors and messages using color and context, this is on by default.

  • strict true enables all strict type-checking options

  • target es2016 as es6 helps to support es6 code

  • sourceMap true generates corresponding .map file

  • rootDir specifies the root directory of input files

  • declaration true generates corresponding .d.ts file

See TypeScript: TSConfig Reference - Docs on every TSConfig option - https://www.typescriptlang.org/tsconfig to learn more.

Testing

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$ echo "console.log('Hello typescript !')" > index.ts

Add scripts to package.json

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{
  "main": "dist/index.js",
  "types": "dist/index.d.ts",
  "scripts": {
    "start": "ts-node index.ts",
    "build": "tsc"
  },
}

Run npm run start to start application without compile.

Run npm run build then node dist/index.js to compile and run applcation as javascript.

References

[1] Create a new node js project in typescript (for beginners) - DEV Community - https://dev.to/rajat19/create-a-new-node-js-project-in-typescript-nao

[2] TypeScript: Documentation - What is a tsconfig.json - https://www.typescriptlang.org/docs/handbook/tsconfig-json.html

[3] TypeScript: Documentation - tsc CLI Options - https://www.typescriptlang.org/docs/handbook/compiler-options.html

[4] TypeScript: TSConfig Reference - Docs on every TSConfig option - https://www.typescriptlang.org/tsconfig

[5] Typescript tsconfig.json全解析 | springleo’s blog - https://lq782655835.github.io/blogs/project/ts-tsconfig.html

[6] https://262.ecma-international.org/7.0/ - https://262.ecma-international.org/7.0/