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TypedArray.prototype.fill()

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 fill() method of TypedArray instances changes all elements within a range of indices in a typed array to a static value. It returns the modified typed array. This method has the same algorithm as Array.prototype.fill().

In this article

Try it

const uint8 = new Uint8Array([0, 0, 0, 0]);
// Value, start position, end position
uint8.fill(4, 1, 3);

console.log(uint8);
// Expected output: Uint8Array [0, 4, 4, 0]

Syntax

js
fill(value)
fill(value, start)
fill(value, start, end)

Parameters

value

Value to fill the typed array with.

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

Zero-based index at which to end filling, converted to an integer. fill() fills up to but not including end.

Return value

The modified typed array, filled with value.

Description

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

Examples

Using fill()

js
new Uint8Array([1, 2, 3]).fill(4); // Uint8Array [4, 4, 4]
new Uint8Array([1, 2, 3]).fill(4, 1); // Uint8Array [1, 4, 4]
new Uint8Array([1, 2, 3]).fill(4, 1, 2); // Uint8Array [1, 4, 3]
new Uint8Array([1, 2, 3]).fill(4, 1, 1); // Uint8Array [1, 2, 3]
new Uint8Array([1, 2, 3]).fill(4, -3, -2); // Uint8Array [4, 2, 3]

Specifications

Specification

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

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