Doodle Press

# JavaScript & TypeScript

JavaScript is the foundation of frontend apps, and TypeScript adds type safety and scalability. Following best practices ensures fewer bugs and cleaner code.

# General Principles

  • Prefer TypeScript for all new projects.
  • Use modern ES6+ features (let/const, arrow functions, destructuring, template literals).
  • Keep functions pure → avoid unexpected side effects.
  • Organize logic into modules → avoid giant utility files.
  • Write self-explanatory code → minimize the need for comments.

# JavaScript Best Practices

  • Always use const unless reassignment is required → then use let.
  • Use strict equality (===) instead of loose equality (==).
  • Prefer array methods (map, filter, reduce) over loops where it improves readability.
  • Avoid modifying built-in prototypes (Array.prototype, etc.).
  • Handle edge cases explicitly (null, undefined, empty strings, 0).

# TypeScript Best Practices

  • Use interfaces and types for data contracts.
interface User {
  id: number
  name: string
  email: string
}
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# Controlled Values

  • Use enums or literal types for controlled values.
type Status = 'active' | 'inactive' | 'pending'
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# Reusability

  • Use generics to create reusable functions.
  • Enable strict mode in tsconfig.json.

# Error Handling

  • Use try/catch with async/await.
  • Narrow error types instead of catching all.
  • Provide meaningful error messages.
try {
  const response = await fetchData()
} catch (err: unknown) {
  if (err instanceof Error) {
    console.error('Error:', err.message)
  }
}
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# Code Organization

  • Group related functions into modules.
  • Avoid giant utility files → split into domains (date.utils.ts, string.utils.ts).
  • Keep imports clean & sorted.
  • Use barrel files (index.ts) for re-exports when appropriate.

# Tooling

  • Use ESLint with TypeScript plugins.
  • Use Prettier for consistent formatting.
  • Enable type-checking in build pipelines.
  • Add unit tests for utility functions and services.

# Benefits of Using TypeScript

  • Type safety → fewer runtime errors.
  • Autocomplete & IntelliSense → faster developer experience.
  • Refactorability → easier to change code without breaking it.
  • Documentation by design → types explain data structures.
  • Confidence → stricter codebase reduces bugs in production.

# Key Takeaway

JavaScript gives flexibility, but TypeScript adds discipline.
Use TypeScript wherever possible to build scalable, maintainable, and reliable frontends.

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