JavaScript Array indexOf()

Definition and Usage

indexOf() The method searches for the specified item in the array and returns its position.

The search starts from the specified position, if no starting position is specified, it starts from the beginning, and ends at the end of the array.

If the item is not found, then indexOf() returns -1.

If the item appears multiple times, then indexOf() The method returns the position of the first occurrence.

Note:The position of the first item is 0, the position of the second item is 1, and so on.

Tip:If you want to search from the end to the beginning, use lastIndexOf() Method.

Example

Example 1

Search for the item "Apple" in the array:

var fruits = ["Banana", "Orange", "Apple", "Mango"];
var a = fruits.indexOf("Apple");

Try It Yourself

Example 2

Search for the item "Apple" in the array, starting from position 4:

var fruits = ["Banana", "Orange", "Apple", "Mango", "Banana", "Orange", "Apple"];
var a = fruits.indexOf("Apple", 4);

Try It Yourself

Syntax

array.indexOf(item, start)

Parameter Value

Parameter Description
item Required. The item to search for.
start Optional. The position where to start the search. Negative values indicate positions counted from the end, then search to the last.

Technical Details

Return Value: A number, representing the position of the specified item, otherwise -1.
JavaScript Version: ECMAScript 5

Browser Support

All browsers fully support indexOf() Method:

Chrome IE Edge Firefox Safari Opera
Chrome IE Edge Firefox Safari Opera
Supported 9.0 Supported Supported Supported Supported

Related Pages

Tutorial:JavaScript Array

Tutorial:JavaScript Array Const

Tutorial:JavaScript Array Methods

Tutorial:JavaScript Array Sorting

Tutorial:JavaScript Array Iteration

Manual:Array lastIndexOf Method