Array type

Learn to define arrays and specify their types.

Array type

In TypeScript, an array is an ordered list of values of the same type. The array type is written in two ways: number[] or Array<number>. The type inside the brackets specifies the type of elements the array holds. The type annotation comes after the variable with :.

let sayilar: number[] = [1, 2, 3];
let isimler: Array<string> = ["Ali", "Ayşe"];

Type checking and inference

When you specify a type for an array, TypeScript prevents adding wrong-typed elements. Even without a type annotation, TypeScript infers the array type from the initial assignment. Writing the explicit type is safer.

let renkler: string[] = ["kırmızı", "mavi"];
renkler.push("yeşil");
// renkler.push(5); // Error

Exercise Prices array

Define a number[] array named fiyatlar with the values 100, 250, 75. Then print the array with console.log.

Show example solution

let fiyatlar: number[] = [100, 250, 75];
console.log(fiyatlar);

Test yourself

What does the `Array<number>` notation specify?
- All elements of the array being of number type
- Elements of the array being of different types
- The array holding only a single number
- The array always starting empty
Show answer

All elements of the array being of number type — The `Array<number>` notation requires every element of the array to be of type `number`; adding a different type gives a compile error.

Specify an array type

let notlar: number____ = [70, 85, 90];

Show answer

let notlar: number[] = [70, 85, 90];

Array type notations

number[]

Short notation for a number array
Array<string>

General notation for a string array
boolean[]

Short notation for a boolean array
Array<number>

General notation for a number array

Next lesson: Array methods

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