Set up TypeScript project From Scratch

Setting Typescript compiler

Step 1: create an empty folder for our project mkdir typescript-project

Step 2: move into folder cd typescript-porject

Step 3: initialize the package.json with the command: npm init -y

Step 4: create index.ts file in src folder with the command: mkdir typescript-project && touch typescript-project/index.js

Step 5: install typescript speedy compiler as dev dependencies with command: npm i -D @swc/cli @swc/core

Step 6: create configuration file .swcrc for swc in typescript-project folder and add this configuration:

{
  "jsc": {
    "parser": {
      "syntax": "typescript",
      "tsx": false,
      "dynamicImport": true,
      "decorators": true
    },
    "transform": {
      "legacyDecorator": true,
      "decoratorMetadata": true
    },
    "target": "es2017",
    "externalHelpers": false,
    "keepClassNames": true,
    "loose": false,
    "minify": {
      "compress": false,
      "mangle": false
    },
    "baseUrl": "src"
  },
  "module": {
    "type": "commonjs"
  }
}

Step 7: install express npm i express and types for express npm i --save-dev @types/express and add the below code into src/index.ts:

import express from 'express';
const app = express();

app.get('/', (_req, res) => {
  res.send('Hello World!');
});

app.listen(3000, () => {
  console.log('Server started on port 3000');
});

Step 8: add build command under scripts to package.json "build": "swc src -d dist --source-maps" and start command
"start": "npm run build && node dist/index.js

Step 9: test if the app work, by running the command: npm run start should print out: Server started on port 3000

Step 10: running the TypeScript compiler every time you make a change can be tedious. To fix this, install npm i ts-node-dev and add dev command to package.json, command: "dev": "ts-node-dev --respawn --transpile-only --ignore-watch node_modules src/index.ts

package.json should look like this:

{
  "name": "setup-project-ts",
  "version": "1.0.0",
  "description": "",
  "main": "dist/index.js",
  "scripts": {
    "start": "npm run build && node dist/index.js",
    "dev": "ts-node-dev --respawn --transpile-only --ignore-watch node_modules src/index.ts",
    "build": "swc src -d dist --source-maps"
  },
  "keywords": [],
  "author": "",
  "license": "ISC",
  "devDependencies": {
    "@swc/cli": "^0.1.57",
    "@swc/core": "^1.3.8",
    "@types/express": "^4.17.14",
    "ts-node-dev": "^2.0.0"
  },
  "dependencies": {
    "express": "^4.18.2"
  }
}

Setting Eslint + Prettier

• Eslint defines the code conventions
• Prettier performs the auto-formatting based on the ESLint rules

Step 1: add needed eslint and prettier dependencies: npm i eslint eslint-config-prettier eslint-plugin-prettier @typescript-eslint/eslint-plugin @typescript-eslint/parser --save-dev

Step 2: create .prettierrc file in typescript-project with content:

{
  "printWidth": 150,
  "tabWidth": 2,
  "singleQuote": true,
  "trailingComma": "all",
  "semi": true,
  "arrowParens": "avoid"
}

Step 3: add prettier-format command to package.json: "prettier-format": "prettier --config .prettierrc src/**/*.ts --write"

Step 4: test prettier by running: npm run prettier-format

Step 5: create .eslintignore file, with content:

/dist

Ignore dist folder when checking code conventions.

Step 6: create .eslintrc file with content:

{
  "parser": "@typescript-eslint/parser",
  "extends": ["prettier", "plugin:@typescript-eslint/recommended", "plugin:prettier/recommended"],
  "parserOptions": {
    "ecmaVersion": 2018,
    "sourceType": "module"
  },
  "rules": {
    "@typescript-eslint/explicit-member-accessibility": 0,
    "@typescript-eslint/explicit-function-return-type": 0,
    "@typescript-eslint/no-parameter-properties": 0,
    "@typescript-eslint/interface-name-prefix": 0,
    "@typescript-eslint/explicit-module-boundary-types": 0,
    "@typescript-eslint/no-explicit-any": "off",
    "@typescript-eslint/ban-types": "off",
    "@typescript-eslint/no-var-requires": "off"
  }
}

Step 7: add lint and lint:fix command to package.json:

"scripts": {
   "lint": "eslint --ignore-path .gitignore --ext .ts src/",
   "lint:fix": "eslint --ignore-path .gitignore --ext .ts src/ --fix"
}

Step 8: check if lint is fixing coding conventions by running command: npm run lint:fix

package.json should look like this:

{
  "name": "setup-project-ts",
  "version": "1.0.0",
  "description": "",
  "main": "dist/index.js",
  "scripts": {
    "start": "npm run build && node dist/index.js",
    "dev": "ts-node-dev --respawn --transpile-only --ignore-watch node_modules src/index.ts",
    "build": "swc src -d dist --source-maps",
    "lint": "eslint --ignore-path .gitignore --ext .ts src/",
    "lint:fix": "eslint --ignore-path .gitignore --ext .ts src/ --fix",
    "prettier-format": "prettier --config .prettierrc  src/**/*.ts --write"
  },
  "keywords": [],
  "author": "",
  "license": "ISC",
  "devDependencies": {
    "@swc/cli": "^0.1.57",
    "@swc/core": "^1.3.8",
    "@types/express": "^4.17.14",
    "@typescript-eslint/eslint-plugin": "^5.40.0",
    "@typescript-eslint/parser": "^5.40.0",
    "eslint": "^8.25.0",
    "eslint-config-prettier": "^8.5.0",
    "eslint-plugin-prettier": "^4.2.1",
    "ts-node-dev": "^2.0.0"
  },
  "dependencies": {
    "express": "^4.18.2"
  }
}

Pre-commit hooks

Step 1: add dependency: npm run --save-dev pre-commit

Step 2: add pre-commit array to your package.json:

{

  "scripts": {
    "start": "npm run build && node dist/index.js",
  },
  "pre-commit": [
    "lint",
    "prettier-format"
  ],
}

Before each commit will run lint and prettier-format.

Code example: https://github.com/DarthRevanXX/typescript-project-example