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TypedArray.prototype.indexOf()

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since September 2016.

The indexOf() method of TypedArray instances returns the first index at which a given element can be found in the typed array, or -1 if it is not present. This method has the same algorithm as Array.prototype.indexOf().

In this article

Try it

const uint8 = new Uint8Array([10, 20, 30, 40, 50]);

console.log(uint8.indexOf(50));
// Expected output: 4

// From position 3
console.log(uint8.indexOf(20, 3));
// Expected output: -1

console.log(uint8.indexOf(51));
// Expected output: -1

Syntax

js
indexOf(searchElement)
indexOf(searchElement, fromIndex)

Parameters

Element to locate in the typed array.

fromIndex Optional

Zero-based index at which to start searching, converted to an integer.

Return value

The first index of searchElement in the typed array; -1 if not found.

Description

See Array.prototype.indexOf() for more details. This method is not generic and can only be called on typed array instances.

Examples

Using indexOf()

js
const uint8 = new Uint8Array([2, 5, 9]);
uint8.indexOf(2); // 0
uint8.indexOf(7); // -1
uint8.indexOf(9, 2); // 2
uint8.indexOf(2, -1); // -1
uint8.indexOf(2, -3); // 0

Specifications

Specification

ECMAScript® 2027 Language Specification
# sec-%typedarray%.prototype.indexof

Browser compatibility

Enable JavaScript to view this browser compatibility table.

See also

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This page was last modified on Jul 10, 2025 by MDN contributors.

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Standard built-in objects
TypedArray
Static methods
1. from()
2. of()
Static properties
1. BYTES_PER_ELEMENT
2. [Symbol.species]
Instance methods
1. at()
2. copyWithin()
3. entries()
4. every()
5. fill()
6. filter()
7. find()
8. findIndex()
9. findLast()
10. findLastIndex()
11. forEach()
12. includes()
13. indexOf()
14. join()
15. keys()
16. lastIndexOf()
17. map()
18. reduce()
19. reduceRight()
20. reverse()
21. set()
22. slice()
23. some()
24. sort()
25. subarray()
26. toLocaleString()
27. toReversed()
28. toSorted()
29. toString()
30. values()
31. with()
32. [Symbol.iterator]()
Instance properties
1. buffer
2. byteLength
3. byteOffset
4. length
Inheritance
Object/Function
Static methods
1. apply()
2. bind()
3. call()
4. toString()
5. [Symbol.hasInstance]()
Static properties
1. displayName
2. length
3. name
4. prototype
5. arguments
6. caller
Instance methods
1. __defineGetter__()
2. __defineSetter__()
3. __lookupGetter__()
4. __lookupSetter__()
5. hasOwnProperty()
6. isPrototypeOf()
7. propertyIsEnumerable()
8. toLocaleString()
9. toString()
10. valueOf()
Instance properties
1. __proto__
2. constructor
Related pages
BigInt64Array
BigUint64Array
Float16Array
Float32Array
Float64Array
Int8Array
Int16Array
Int32Array
Uint8Array
Uint8ClampedArray
Uint16Array
Uint32Array