How to get index of an item in an array in JavaScript

#javascript #array

Last updated on Oct 31, 2021 by Suraj Sharma



In this tutorial, you’ll learn how you can get the index of an item in an array in JavaScript using array’s built-in methods.


Using Array.indexOf


The indexOf method returns the index of the first matched item from a given array. However, it returns -1 if the item is not present in the array.


Example

const vehicles = ['Cars', 'Buses', 'Trains', 'Airplanes'];

vehicles.indexOf('Bikes') // -1

vehicles.indexOf('Trains') // 2


Using Array.findIndex


The findIndex method is not supported in older browsers. This method accepts a callback function, which returns an index of the item when the condition inside it returns true.


Example

const places = ['Toronto', 'Mumbai', 'Melbourne', 'Berlin'];

vehicles.findIndex(place=>place==='New York')
// -1

vehicles.findIndex(place=>place==='Mumbai')
// 1


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Suraj Sharma is a Full Stack Software Engineer. He holds a B.Tech degree in Computer Science & Engineering from NIT Rourkela.