TypeScript入門~型・環境構築~

let a: number = 1
let b: string = 'hello'
let c: boolean[] = [true, false]

ts1 % npm init
ts1 % npm i -D typescript tslint @types/node

ts1 % ./node_modules/.bin/tsc -v
Version 4.5.4

{
  "compilerOptions": {
    "lib": ["es2015"],
    "module": "commonjs",
    "outDir": "dist",
    "sourceMap": true,
    "strict": true,
    "target": "es2015",
  },
  "include": [
    "src"
  ]
}

let a = true;
const b = false;

let num1 = 9007199254740991;
const num2 = -9007199254740991;

let str1 = "あいうえお";
const str2 = "アイウエオ";

let boo3: boolean = true;
let num3: number = 123;
let str3: string = "aiueo";

let arrayA = [1, 2, 3];
let arrayB: number[] = [2, 3, 4];
let arrayC: Array<number> = [3, 4, 5];

let tuppleA: [string, string, number] = ["液晶ビエラ", "Sony", 120000];
let tuppleC: [string, number, boolean] = ["液晶ビエラ", 120000, false];

enum Country {
  Japan = "日本",
  China = "中国",
  Korea = 123,
}

console.log(Country.Japan); // => 日本

ts1 % yarn add -D eslint @typescript-eslint/eslint-plugin @typescript-eslint/parser

ts1 % ./node_modules/.bin/eslint -v    
v8.5.0

ts1 % ./node_modules/.bin/eslint --init
✔ How would you like to use ESLint? · style
✔ What type of modules does your project use? · esm
✔ Which framework does your project use? · none
✔ Does your project use TypeScript? · No / Yes
✔ Where does your code run? · browser
✔ How would you like to define a style for your project? · guide
✔ Which style guide do you want to follow? · google
✔ What format do you want your config file to be in? · JavaScript
Checking peerDependencies of eslint-config-google@latest
The config that you've selected requires the following dependencies:

@typescript-eslint/eslint-plugin@latest eslint-config-google@latest eslint@>=5.16.0 @typescript-eslint/parser@latest
✔ Would you like to install them now with npm? · No / Yes
Installing @typescript-eslint/eslint-plugin@latest, eslint-config-google@latest, eslint@>=5.16.0, @typescript-eslint/parser@latest
npm WARN ts1@1.0.0 No description
npm WARN ts1@1.0.0 No repository field.

+ eslint-config-google@0.14.0
+ eslint@8.5.0
+ @typescript-eslint/parser@5.8.1
+ @typescript-eslint/eslint-plugin@5.8.1
removed 2 packages, updated 4 packages and audited 161 packages in 10.241s

6 packages are looking for funding
  run `npm fund` for details

found 0 vulnerabilities

Successfully created .eslintrc.js file in /Users/noricgeographic/repositories/sandbox/ts1

ts1 % cat .eslintrc.js 
module.exports = {
  'env': {
    'browser': true,
    'es2021': true,
  },
  'extends': [
    'google',
  ],
  'parser': '@typescript-eslint/parser',
  'parserOptions': {
    'ecmaVersion': 13,
    'sourceType': 'module',
  },
  'plugins': [
    '@typescript-eslint',
  ],
  'rules': {
  },
};

module.exports = {
  'root': true,
  'parser': '@typescript-eslint/parser',
  'parserOptions': {
    'project': './tscofing.json',
  },
  'plugins': [
    '@typescript-eslint',
  ],
  'extends': [
    'eslint:recommended',
    'plugin:@typescript-eslint/eslint-recommended',
    'plugin:@typescript-eslint/recommended',
    'plugin:@typescript-eslint/recommended-requiring-type-checking',
  ],
};

TS7006: Parameter 'n' implicitly has an 'any' type.

1 function squareOf(n) {
                    ~

TS5024: Compiler option 'sourceMap' requires a value of type boolean.

6     "sourceMap": "true",
                   ~~~~~~

error TS18003: No inputs were found in config file '/Users/noricgeographic/repositories/sandbox/ts1/tsconfig.json'. Specified 'include' paths were '["src"]' and 'exclude' paths were '["dist"]'.