indexof array js code example

Example 1: get index of element in array js

const beasts = ['ant', 'bison', 'camel', 'duck', 'bison'];

console.log(beasts.indexOf('bison'));
// expected output: 1

// start from index 2
console.log(beasts.indexOf('bison', 2));
// expected output: 4

console.log(beasts.indexOf('giraffe'));
// expected output: -1

//*** Thanks to MDN Web Docs ***//
//https://developer.mozilla.org/fr/docs/Web/JavaScript/Reference/Objets_globaux/Array/indexOf

Example 2: javasript array indexof

var array = [2, 9, 9];
array.indexOf(2);     // 0
array.indexOf(7);     // -1
array.indexOf(9, 2);  // 2
array.indexOf(2, -1); // -1
array.indexOf(2, -3); // 0

Example 3: JavaScript Array Methods indexOf()

let days = ['Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday'];
console.log(days.indexOf('Sunday'));
// --> -1, mert nem található meg

let days = ['Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday'];
console.log(days.indexOf('Monday'));
// --> 0