Array Index Of 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: js array return only certain positions

const every_nth = (arr, nth) => arr.filter((e, i) => i % nth === nth - 1); console.log(every_nth([1, 2, 3, 4, 5, 6], 1)); console.log(every_nth([1, 2, 3, 4, 5, 6], 2)); console.log(every_nth([1, 2, 3, 4, 5, 6], 3)); console.log(every_nth([1, 2, 3, 4, 5, 6], 4));  // OUTPUT  [1,2,3,4,5,6] [2,4,6] [3,6] [4]

Example 3: js get index of item in array

array.indexOf("item");

Example 4: 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 5: how to get the index of an array in javascript

search = (arr, item) => { return arr.indexOf(item); }

Example 6: get array by array of indices js

var resultArr = indexArr.map(i => fruitier[i])