TypeScript Arrays & Tuples - Complete Guide

Introduction

Let's learn TypeScript arrays and tuples!

What You Will Learn

• Typed arrays
• Readonly arrays
• Tuples
• Array methods with types

Prerequisites

• Functions

Typed Arrays!

Two ways to type arrays!

// Syntax 1: Type[]
let numbers: number[] = [1, 2, 3];
let names: string[] = ["John", "Jane"];

// Syntax 2: Array<Type>
let numbers2: Array<number> = [1, 2, 3];

Readonly Arrays!

Prevent modification!

let numbers: readonly number[] = [1, 2, 3];
// numbers.push(4); // Error!

Tuples!

Arrays with fixed length and known types!

let person: [string, number] = ["John", 30];
let user: [number, string, boolean] = [1, "j@j.com", true];

Array Methods!

TypeScript gives you type safety with array methods!

let numbers: number[] = [1, 2, 3];
numbers.map(n => n * 2); // [2,4,6] - type is number[]!
numbers.filter(n => n > 1); // [2,3] - number[]!

Best Practices

1. Prefer Type[] syntax: More common!
2. Use readonly when possible: Immutability!
3. Tuple lengths fixed: Don't exceed!

Summary

TypeScript arrays and tuples!

Related Articles

• Objects & Object Types

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