TypeScript
JavaScript
Tipos
Desenvolvimento
React Native
Mobile

TypeScript for Applications: Typed Development Guide

TypeScript adds types to JavaScript. For applications, this means fewer bugs, better DX, and more maintainable code. This guide presents how to use TypeScript in mobile development.

What is TypeScript

Definition

JavaScript superset with static types.

Relationship with JS

All valid JS is valid TS.

Compilation

Compiles to JavaScript.

Adoption

Massive growth. Standard for serious projects.

Why TypeScript

Catch Errors Early

Errors at compile time, not runtime.

Autocompletion

IDE knows what is possible.

Refactoring

Large-scale secure changes.

Documentation

Types are living documentation.

Team Scale

Multiple developers aligned.

Basic Types

Primitives

string, number, boolean, null, undefined.

Arrays

number[], Array.

Objects

{ name: string; age: number }.

###Any

Opt-out of types. Avoid.

Unknown

Like safe when you don't know.

Interfaces and Types

Interface

Defines shape of objects.

Type Alias

Name for any type.

###Difference

Interface extends, type for unions.

When to Use

Interface for objects, type for composition.

Advanced Types

###Union

string | number.

Intersection

TypeA & TypeB.

Generics

Array, function that works with any type.

Literal Types

"success" | "error".

Utility Types

Partial, Required, Pick, Omit.

TypeScript in React Native

###Setup

Template TypeScript available.

###Components

Typed props and state.

Navigation

React Navigation with types.

State

Redux/Zustand with types.

###API

Typed responses.

Typing Components

Props Interface

interface Props { title: string; onPress: () => void; }

Optional Props

title?: string.

Default Props

Default values with destructuring.

###Children

React.ReactNode.

Typing APIs

Response Types

interface User { id: string; name: string; }

Generics

async function fetch(url: string): Promise

Zod/Yup

Runtime validation + types.

State Management

Redux

createSlice with types.

Zustand

Store interface.

Context

Type of context value.

Navigation Types

React Navigation

StackParamList for typed routes.

Route Params

Parameters typed between screens.

useNavigation

Typed hook.

Configuration

tsconfig.json

Build options.

strict Mode

Maximum security. Always use.

Path Aliases

@/components for clean imports.

Migration from JS to TS

Gradual

Rename .js to .ts incrementally.

allowJs

Allow JS while migrating.

any Temporary

Use to migrate quickly, remove later.

Strict Later

Enable strict after migrating.

Patterns

Discriminated Unions

type State = { status: 'loading' } | { status: 'success'; date: Date }.

Exhaustive Checks

Switch that guarantees all cases.

Const Assertions

as const for literals.

Common Errors

any Everywhere

Loses type benefits.

Ignoring Errors

// @ts-ignore unnecessarily.

Over-Typing

Too complex types.

Not Using Strict

Misses important validations.

Tools

VS Code

Excellent native support.

ESLint

@typescript-eslint for linting.

Prettier

Consistent formatting.

##Performance

Compile Time

Can be slow on large projects.

Runtime

Zero overhead. Types are removed.

Bundle Size

Same as JavaScript.

Conclusion

TypeScript is an investment that pays in quality and productivity. For apps, it means fewer bugs in production, secure refactoring, and easier onboarding of new devs.

##FAQs

1) Is TypeScript slower? Compilation yes. Runtime there is no difference.

2) Do I need to type everything? TypeScript infers a lot. Type as necessary.

3) Is it valid for a small project? Yes. Benefits from the beginning.

4) How to start with an existing project? Gradually. File by file.

5) Does TypeScript work with React Native? Perfectly. Official template available.

Also read

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