Get index of element in an array JavaScript

> indexOf index_of method

Description

Get the index of the array position where the element is allocated.

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

arr.indexOf( searchElement, fromIndex )

API Array.prototype.indexOf()