TypeScript

Best Coding Practices:

Standard Area	Recommended Practice	Purpose / Example
Variable Declaration	Immutability: Use `const` by default. Use `let` only if reassignment is strictly needed. Never use `var`.	Purpose: Makes code logic predictable; reduces side effects.
Booleans	Named as Questions: Boolean variables must strictly use prefixes like `is`, `has`, `should`, or `can`.	Purpose: Immediate semantic understanding. Bad: `const visible = true` Good: `const isVisible = true`
Asynchronous Logic	Async/Await: Prefer `async/await` syntax over `.then()` chains.	Purpose: Makes async code look like synchronous code; easier to debug. Exception: Parallel execution using `Promise.all`.
Imports	Type Imports: Use `import type { ... }` when importing interfaces or types.	Purpose: Helps the bundler remove non-code imports, reducing bundle size. Example: `import type { User } from './types'`
Arrays	Generics Syntax: Prefer `Array<Type>` for complex types and `Type[]` for primitives.	Purpose: Improves readability. Primitive: `string[]` Complex: `Array<Record<string, unknown>>`
String Handling	Template Literals: Use backticks (`) for concatenation instead of `+`.	Purpose: Cleaner syntax and easier multi-line strings. Example: `Hello ${name}` is better than `'Hello ' + name`
Switch Statements	Exhaustiveness Check: Use a `never` type check in the `default` case of a switch statement.	Purpose: Ensures that if you add a new case to a Union type, the compiler forces you to handle it in the switch.

Best Linting Practises:

Tool	Rule Type	Typical Setting
Prettier	Style / Formatting	Indentation: 2 or 4 spaces (No Tabs). Quotes: Single or Double (choose one). Semicolons: Always or Never (choose one).
ESLint (`@typescript-eslint`)	Code Quality / Best Practice	`@typescript-eslint/no-unused-vars`: Disallow unused variables. `@typescript-eslint/explicit-function-return-type`: (Optional but helpful) Require function return types. `no-console`: Disallow `console.log` (especially in production code).
ESLint (`eslint-plugin-import`)	Module / Import Quality	`import/order`: Enforce a consistent order for imports. `import/no-unresolved`: Ensure imports point to existing files.

Recommended Extensions for VScode:

Extension Name	Publisher	Function
ESLint	Dirk Baeumer	Integrates ESLint into VS Code, showing errors and warnings directly in the editor and providing quick fixes. Essential for linting enforcement.
Prettier – Code formatter	Esben Petersen	Formats code using Prettier. Essential for enforcing consistent code style.
EditorConfig for VS Code	EditorConfig	Maintains consistent coding styles across multiple developers and editors by using a `.editorconfig` file in the repository root.

VS Code configuration file for Typescript Linting:

{
  "editor.formatOnSave": true,
  "editor.defaultFormatter": "esbenp.prettier-vscode",
  "editor.codeActionsOnSave": {
    "source.fixAll.eslint": "explicit"
  },
  "[typescript]": {
    "editor.defaultFormatter": "esbenp.prettier-vscode"
  },
  "[typescriptreact]": {
    "editor.defaultFormatter": "esbenp.prettier-vscode"
  }
}

Recommended TS Config file:

export = {
  rules: {
    '@typescript-eslint/ban-ts-comment': 'error',
    'no-array-constructor': 'off',
    '@typescript-eslint/no-array-constructor': 'error',
    '@typescript-eslint/no-duplicate-enum-values': 'error',
    '@typescript-eslint/no-empty-object-type': 'error',
    '@typescript-eslint/no-explicit-any': 'error',
    '@typescript-eslint/no-extra-non-null-assertion': 'error',
    '@typescript-eslint/no-misused-new': 'error',
    '@typescript-eslint/no-namespace': 'error',
    '@typescript-eslint/no-non-null-asserted-optional-chain': 'error',
    '@typescript-eslint/no-require-imports': 'error',
    '@typescript-eslint/no-this-alias': 'error',
    '@typescript-eslint/no-unnecessary-type-constraint': 'error',
    '@typescript-eslint/no-unsafe-declaration-merging': 'error',
    '@typescript-eslint/no-unsafe-function-type': 'error',
    'no-unused-expressions': 'off',
    '@typescript-eslint/no-unused-expressions': 'error',
    'no-unused-vars': 'off',
    '@typescript-eslint/no-unused-vars': 'error',
    '@typescript-eslint/no-wrapper-object-types': 'error',
    '@typescript-eslint/prefer-as-const': 'error',
    '@typescript-eslint/prefer-namespace-keyword': 'error',
    '@typescript-eslint/triple-slash-reference': 'error',
    '@typescript-eslint/await-thenable': 'error',
    '@typescript-eslint/ban-ts-comment': 'error',
    'no-array-constructor': 'off',
    '@typescript-eslint/no-array-constructor': 'error',
    '@typescript-eslint/no-array-delete': 'error',
    '@typescript-eslint/no-base-to-string': 'error',
    '@typescript-eslint/no-duplicate-enum-values': 'error',
    '@typescript-eslint/no-duplicate-type-constituents': 'error',
    '@typescript-eslint/no-empty-object-type': 'error',
    '@typescript-eslint/no-explicit-any': 'error',
    '@typescript-eslint/no-extra-non-null-assertion': 'error',
    '@typescript-eslint/no-floating-promises': 'error',
    '@typescript-eslint/no-for-in-array': 'error',
    'no-implied-eval': 'off',
    '@typescript-eslint/no-implied-eval': 'error',
    '@typescript-eslint/no-misused-new': 'error',
    '@typescript-eslint/no-misused-promises': 'error',
    '@typescript-eslint/no-namespace': 'error',
    '@typescript-eslint/no-non-null-asserted-optional-chain': 'error',
    '@typescript-eslint/no-redundant-type-constituents': 'error',
    '@typescript-eslint/no-require-imports': 'error',
    '@typescript-eslint/no-this-alias': 'error',
    '@typescript-eslint/no-unnecessary-type-assertion': 'error',
    '@typescript-eslint/no-unnecessary-type-constraint': 'error',
    '@typescript-eslint/no-unsafe-argument': 'error',
    '@typescript-eslint/no-unsafe-assignment': 'error',
    '@typescript-eslint/no-unsafe-call': 'error',
    '@typescript-eslint/no-unsafe-declaration-merging': 'error',
    '@typescript-eslint/no-unsafe-enum-comparison': 'error',
    '@typescript-eslint/no-unsafe-function-type': 'error',
    '@typescript-eslint/no-unsafe-member-access': 'error',
    '@typescript-eslint/no-unsafe-return': 'error',
    '@typescript-eslint/no-unsafe-unary-minus': 'error',
    'no-unused-expressions': 'off',
    '@typescript-eslint/no-unused-expressions': 'error',
    'no-unused-vars': 'off',
    '@typescript-eslint/no-unused-vars': 'error',
    '@typescript-eslint/no-wrapper-object-types': 'error',
    'no-throw-literal': 'off',
    '@typescript-eslint/only-throw-error': 'error',
    '@typescript-eslint/prefer-as-const': 'error',
    '@typescript-eslint/prefer-namespace-keyword': 'error',
    'prefer-promise-reject-errors': 'off',
    '@typescript-eslint/prefer-promise-reject-errors': 'error',
    'require-await': 'off',
    '@typescript-eslint/require-await': 'error',
    '@typescript-eslint/restrict-plus-operands': 'error',
    '@typescript-eslint/restrict-template-expressions': 'error',
    '@typescript-eslint/triple-slash-reference': 'error',
    '@typescript-eslint/unbound-method': 'error',
  },
};

Scripts to add to package.json

"scripts": {
  "type-check": "tsc --noEmit",
  "lint": "eslint . --ext .ts,.tsx",
  "lint:fix": "eslint . --ext .ts,.tsx --fix",
  "format:check": "prettier --check \"**/*.{ts,tsx,json,css,md}\""
}

Commands to check on whether repository is following Lint:

npm run lint
npm run format:check