The indexOf() method in JavaScript is used to find the index of the first occurrence of a specified element in an array.
Syntax
array.indexOf(element, start)Parameters:
- element: This parameter holds the element whose index will be returned.
- start: This parameter is optional and it holds the starting point of the array, where to begin the search the default value is 0.
Return value: This method returns the index of the first occurrence of the element. If the element cannot be found in the array, then this method returns -1.
JavaScript Array indexOf() Method Examples
Example 1: Finding Index of Element in Array
This code demonstrates the use of the indexOf() method to find the index of the element "gfg" in the array name. The index of "gfg" is stored in the variable a and then logged to the console.
let name = ['gfg', 'cse', 'geeks', 'portal'];
a = name.indexOf('gfg')
// Printing result of method
console.log(a)
Output
0
Example 2: Searching Element in Array
This code demonstrates the use of the indexOf() method to find the index of a specific element (2) in an array (A). It returns the index of the first occurrence of the element in the array (1 in this case). If the element is not found, it returns -1.
// Taking input as an array A
// having some elements.
let A = [1, 2, 3, 4, 5];
// indexOf() method is called to
// test whether the searching element
// is present in given array or not.
a = A.indexOf(2)
// Printing result of method.
console.log(a);
Output:
1We have a complete list of Javascript Array methods, to check those please go through this Javascript Array Complete reference article.
Supported Browsers:
- Google Chrome 1 and above
- Edge 12 and above
- Firefox 1.5 and above
- Internet Explorer 9 and above
- Opera 9.5 and above
- Safari 3 and above
We have a Cheat Sheet on Javascript where we covered all the important topics of Javascript to check those please go through Javascript Cheat Sheet-A Basic guide to JavaScript.