CodeBlanks Logo Icon CodeBlanks
Login Register

What is a tuple?

Learn tuple, fixed-length ordered arrays.

What is a tuple?

A tuple is an array with a fixed length and a specific type at each position. While a regular array holds elements of one type, a tuple lets you place different types side by side in a specific order. The order of types matters: [string, number] and [number, string] are different tuple types.

let kisi: [string, number] = ["Ayşe", 28];
//  two-element, ordered tuple

A tuple is the type-safe way to group a few related values in a single variable.

Tuple type syntax

A tuple type is written as a comma-separated list of types inside square brackets: [type1, type2, ...]. The number of types sets the tuple's length. You can use the string, number and boolean types you have already seen at any position.

let nokta: [number, number] = [3, 4];
let bayrak: [boolean, string] = [true, "aktif"];

A wrong number of elements or a wrong type order produces a compile error.

Practice Name and age tuple

Declare a variable named kisi with type [string, number] and value ["Ayşe", 28]. Print the age value with console.log.

Starter code

index.ts
// kisi adında bir tuple tanımla
// birinci öğe string, ikinci öğe number
// değer olarak bir isim ve bir yaş gir
// kisi'nin ikinci öğesini yazdır

Sample solution

index.ts
let kisi: [string, number] = ["Ayşe", 28];
console.log(kisi[1]);

Expected output

28

Questions and answers

Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.

1 What is the key feature that distinguishes a tuple from a regular array in TypeScript?

  • It has a fixed length and a specific type at each position Correct answer
  • It can hold only numbers
  • It has no length limit
  • It can hold only strings

Explanation: A tuple's length is fixed by its type list and each position has its own type; a regular array holds elements of one type.

2 Complete the tuple type

Question 
let nokta: [number, ____] = [3, 4];
Answer 
let nokta: [number, number] = [3, 4];

Explanation: Since the second position is also a number, the tuple type must be <code>[number, number]</code>; it matches the value <code>[3, 4]</code>.

3 Tuple parts

Term Meaning
[string, number] Two-element ordered tuple type
number[] Array where all elements share one type
[boolean, boolean] Two-element boolean tuple
Tuple Fixed-length and ordered array

All lessons in Beginner

1 TypeScript intro and setup

  1. What is TypeScript?
  2. Why TypeScript?
  3. tsc compiler
  4. tsconfig basics
  5. Summary - TypeScript basics

2 Primitive types

  1. string type
  2. number type
  3. boolean type
  4. let and const
  5. Summary - Primitive types

3 Arrays

  1. Array type
  2. Array methods
  3. readonly arrays
  4. Multidimensional arrays
  5. Summary - Arrays

4 Tuples

  1. What is a tuple?
  2. Tuple usage
  3. readonly tuple
  4. Summary - Tuple

5 Enums

  1. Numeric enum
  2. String enum
  3. const enum
  4. Enum members
  5. Summary - Enum

6 any, unknown, never

  1. any type
  2. unknown type
  3. never type
  4. void type
  5. Summary - Special types

7 Type annotation

  1. Variable annotation
  2. Parameter annotation
  3. Return type annotation
  4. Summary - Type annotation

8 Type inference

  1. Basic inference
  2. Inference with const
  3. Best common type
  4. Summary - Type inference

9 Objects

  1. Object type
  2. Optional properties
  3. Readonly properties
  4. Summary - Objects

10 Functions

  1. Function declaration
  2. Optional and default params
  3. Rest params
  4. Function overloads
  5. Summary - Functions

11 Arrow functions

  1. Arrow syntax
  2. this with arrow
  3. Arrow type
  4. Summary - Arrow functions

12 Interfaces

  1. What is an interface?
  2. Property types
  3. Interface vs type alias
  4. Summary - Interfaces

13 Type alias

  1. What is a type alias?
  2. Composition with alias
  3. Alias vs interface
  4. Summary - Type alias

14 Union and intersection

  1. Union types
  2. Intersection types
  3. Literal types
  4. Summary - Union & intersection

15 null and undefined

  1. null vs undefined
  2. Optional chaining
  3. Nullish coalescing
  4. Summary - null & undefined

16 Strict mode

  1. strict: true
  2. strictNullChecks
  3. strictFunctionTypes
  4. Summary - Strict mode

17 Project: Shopping cart

  1. Cart design
  2. Add product
  3. Total calculation
  4. Apply discount
  5. Integration

18 Project: Todo CLI

  1. Task model
  2. Add and list
  3. Completion
  4. Filtering
  5. Integration

19 Project: Library

  1. Book model
  2. Add and search
  3. Borrow
  4. Return
  5. Integration

20 Beginner final

  1. Challenge 1: Types
  2. Challenge 2: Functions
  3. Challenge 3: Unions
  4. Challenge 4: Mini app