# TypeScript Express 環境、建置 (tsc、tslint、prettier、ts-node)

### Express 專案上使用
https://khalilstemmler.com/blogs/typescript/node-starter-project/

***Install Setup***

npm init -y
npm install typescript --save-dev
npm install @types/node
npm install --save-dev ts-node nodemon
npm install --save-dev rimraf

yarn add -D typescript

***Create*** `tsconfig.json`

{
  "compilerOptions": {
    "target": "es5",                          
    "module": "commonjs",                    
    "lib": ["es6"],                     
    "allowJs": true,
    "outDir": "dist",                          
    "strict": false,         
  },
  "include": ["src"]
}

***Create ts*** `src/index.ts`

// src/index.ts

function squareOf(n: number): number {
  return n * n
}
squareOf(6)

squareOf("7") 
// error TS2345: Argument of type '"6"' is not assignable to parameter of type 'number'.

***nodemon***

// nodemon.json
{
  "watch": ["src"],
  "ext": ".ts,.js",
  "ignore": [],
  "exec": "ts-node ./src/index.ts"
}

***package*** 設定

  "scripts": {
    "dev": "nodemon",
    "build": "rimraf ./dist && tsc",
    "start": "npm run build && node dist/index.js"
  },

`npm run dev` - 開發
`npm run build` - 移除舊的 dist 輸出新的 dist

***vscode prettier***

// vscode/setting

  "[typescript]": {
    "editor.defaultFormatter": "vscode.typescript-language-features"
  },

.prettierrc

{
  "arrowParens": "always",
  "bracketSpacing": false,
  "htmlWhitespaceSensitivity": "css",
  "insertPragma": false,
  "jsxBracketSameLine": false,
  "jsxSingleQuote": false,
  "printWidth": 120,
  "proseWrap": "always",
  "quoteProps": "as-needed",
  "requirePragma": false,
  "semi": false,
  "singleQuote": true,
  "tabWidth": 2,
  "trailingComma": "all",
  "useTabs": false,
  "vueIndentScriptAndStyle": false
}

***vscode tslint***

// tslint.json

{
  "defaultSeverity": "error",
  "extends": ["tslint:recommended"],
  "jsRules": {},
  "rules": {
    "semicolon": false,
    "trailing-comma": false
  },
  "rulesDirectory": []
}