index.md

Arrays

An array is created with the type of data it holds, followed by square brackets [].

const numbers = [10, 30, 40, 5, 3, 30];
const values = [10, 'Fees', 40, 'Product', 3, 30];

function greaterThan10(data: number[]) {
  return data.filter((n) => n > 10);
}
greaterThan10(numbers);

function filterNumbers(data: (string | number)[]) {
  return data.filter((item) => typeof item === 'number');
}
filterNumbers(values);

const data: (string | number)[][] = [
  ['Lord of the Rings', 80],
  ['Game of Thrones', 120],
];

• Here, numbers is an array containing only numbers, and values is an array containing a mix of numbers and strings.

The greaterThan10 function filters out numbers greater than 10 from an array of numbers.

The filterNumbers function filters out only the numbers from an array containing a mix of numbers and strings.

Lastly, data is a two-dimensional array containing both strings and numbers.

Alternative Syntax

There is an alternative syntax, where we use Array<type>, with type being the data type inside the array.

const numbers = [10, 30, 40, 5, 3, 30];

function greatherThan10(data: Array<number>) {
  return data.filter((n) => n > 10);
}