TypeScript Best Practices Every Developer Should Know in 2024

Why TypeScript Matters

TypeScript has become the standard for large-scale JavaScript applications. It catches errors at compile time, improves code documentation, and enables better tooling support.

Enable Strict Mode

Always enable strict mode in your tsconfig.json. This catches more errors and enforces better practices:

Key Strict Options

strict: true (enables all strict checks)

noImplicitAny: Catches untyped variables

strictNullChecks: Prevents null/undefined errors

strictFunctionTypes: Ensures function type safety

Use Type Inference Wisely

TypeScript's type inference is powerful. Don't over-annotate when the compiler can figure it out:

Good Practice

Let TypeScript infer types for:

Variable assignments from literals

Function return types (when obvious)

Array methods like map and filter

Explicit Types For

Function parameters (always)

Public API boundaries

Complex object structures

Prefer Interfaces Over Types

For object shapes, prefer interfaces:

Interfaces can be extended and merged

Better error messages

More performant for large codebases

Use type aliases for:

Union types

Utility types

Function types

Leverage Utility Types

TypeScript provides powerful built-in utility types:

Partial — Makes all properties optional

Required — Makes all properties required

Pick — Selects specific properties

Omit — Removes specific properties

Record — Creates an object type with specific keys

Discriminated Unions

Use discriminated unions for type-safe state management:

Define a common property (like 'type' or 'status') that TypeScript can use to narrow types automatically.

Avoid 'any'

The 'any' type defeats the purpose of TypeScript. Instead use:

unknown — For truly unknown types (requires type checking)

never — For impossible states

Generic constraints — For flexible but type-safe code

Advanced Patterns

Const Assertions

Use 'as const' to create literal types:

This ensures arrays are readonly tuples and objects have literal property types.

Template Literal Types

Create powerful string types:

Combine literal types with template strings for type-safe string manipulation.

Conditional Types

Build types that change based on conditions:

Useful for creating flexible utility types that adapt to input types.