TypeScript - get index of item in array

In this article, we would like to show you how to get the index of item in an array in TypeScript.

Quick solution:

const numbers: number[] = [1, 2, 3];

const result = numbers.indexOf(2);
console.log(result); // 1

Practical examples

In this example, we use indexOf() method to find the index of the specific item in the numbers array.

const numbers: number[] = [1, 2, 3];

console.log(numbers.indexOf(1)); // 0
console.log(numbers.indexOf(2)); // 1
console.log(numbers.indexOf(5)); // -1

Output:

0
1
-1

Example with an array of strings:

const letters: string[] = ['A', 'B', 'C'];

console.log(letters.indexOf('A')); // 0
console.log(letters.indexOf('B')); // 1
console.log(letters.indexOf('X')); // -1

Output:

0
1
-1

Note:

If the specified value is not present in the array, the indexOf() method returns -1.

See also

1. JavaScript - get index of item in array