Tuple usage

Learn to create tuples and access their elements.

Accessing tuple elements

You access tuple elements by index just like arrays: t[0] returns the first element and t[1] the second. TypeScript knows the exact type at each index, so t[0] on a [string, number] tuple is of type string.

let p: [string, number] = ["x", 5];
console.log(p[0]);  // "x"
console.log(p[1]);  // 5

Because the index type is correct, the compiler asks for no extra conversion.

Tuple destructuring

You use destructuring to pull a tuple's elements into separate variables: let [a, b] = t. This assigns the first element to a and the second to b. Each variable receives the type of its position.

let p: [string, number] = ["x", 5];
let [ad, yas] = p;
//  ad: string, yas: number

Destructuring is the short way to unfold a tuple into named variables in one line.

Exercise Name and price with destructuring

Declare a tuple variable named urun with type [string, number] and value ["kalem", 15]. Destructure it into ad and fiyat. Print the value of ad with console.log.

Show example solution

let urun: [string, number] = ["kalem", 15];
let [ad, fiyat] = urun;
console.log(ad);

Test yourself

In <code>let p: [string, number] = ["x", 5]</code>, what does <code>p[1]</code> return?
- true
- 5
- undefined
- "x"
Show answer

5 — The second position is of type <code>number</code> with value <code>5</code>; <code>p[0]</code> would return <code>"x"</code>.

Split the tuple with destructuring

let bilgi: [string, number] = ["saat", 12];
let [birim, deger] = ____;

Show answer

let bilgi: [string, number] = ["saat", 12];
let [birim, deger] = bilgi;

Access and destructuring

t[0]

Access the first element
t[1]

Access the second element
let [a, b] = t

Unfold the tuple into two variables
Destructuring

Split tuple elements into named variables

Next lesson: readonly tuple

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