Float32Array() constructor

The Float32Array() typed array constructor creates a new Float32Array object, which is, an array of 32-bit floating point numbers (corresponding to the C float data type) in the platform byte order. If control over byte order is needed, use DataView instead. The contents are initialized to 0. Once established, you can reference elements in the array using the object's methods, or using standard array index syntax (that is, using bracket notation).


new Float32Array(); // new in ES2017
new Float32Array(length);
new Float32Array(typedArray);
new Float32Array(object);

new Float32Array(buffer);
new Float32Array(buffer, byteOffset);
new Float32Array(buffer, byteOffset, length);



When called with a length argument, an internal array buffer is created in memory, of size length multiplied by BYTES_PER_ELEMENT bytes, containing zeros.


When called with a typedArray argument, which can be an object of any of the typed array types (such as Int32Array), the typedArray gets copied into a new typed array. Each value in typedArray is converted to the corresponding type of the constructor before being copied into the new array. The length of the new typed array will be same as the length of the typedArray argument.


When called with an object argument, a new typed array is created as if by the TypedArray.from() method.

buffer, byteOffset, length

When called with a buffer, and optionally a byteOffset and a length argument, a new typed array view is created that views the specified ArrayBuffer. The byteOffset and length parameters specify the memory range that will be exposed by the typed array view. If both are omitted, all of buffer is viewed; if only length is omitted, the remainder of buffer is viewed.


Different ways to create a Float32Array

// From a length
var float32 = new Float32Array(2);
float32[0] = 42;
console.log(float32[0]); // 42
console.log(float32.length); // 2
console.log(float32.BYTES_PER_ELEMENT); // 4

// From an array
var arr = new Float32Array([21,31]);
console.log(arr[1]); // 31

// From another TypedArray
var x = new Float32Array([21, 31]);
var y = new Float32Array(x);
console.log(y[0]); // 21

// From an ArrayBuffer
var buffer = new ArrayBuffer(16);
var z = new Float32Array(buffer, 0, 4);

// From an iterable
var iterable = function*(){ yield* [1,2,3]; }();
var float32 = new Float32Array(iterable);
// Float32Array[1, 2, 3]


ECMAScript Language Specification (ECMAScript)
# sec-typedarray-constructors

Browser compatibility

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Compatibility notes

Starting with ECMAScript 2015, Float32Array constructors require to be constructed with a new operator. Calling a Float32Array constructor as a function without new, will throw a TypeError from now on.

var dv = Float32Array([1, 2, 3]);
// TypeError: calling a builtin Float32Array constructor
// without new is forbidden
var dv = new Float32Array([1, 2, 3]);

See also