Float64Array() constructor
The Float64Array()
typed array constructor creates a new
Float64Array
object, which is, an array of 64-bit floating point numbers
(corresponding to the C double
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).
Syntax
new Float64Array(); // new in ES2017
new Float64Array(length);
new Float64Array(typedArray);
new Float64Array(object);
new Float64Array(buffer);
new Float64Array(buffer, byteOffset);
new Float64Array(buffer, byteOffset, length);
Description
Parameters
length
-
When called with a
length
argument, an internal array buffer is created in memory, of sizelength
multiplied byBYTES_PER_ELEMENT
bytes, containing zeros. typedArray
-
When called with a
typedArray
argument, which can be an object of any of the non-bigint typed-array types (such asInt32Array
), thetypedArray
gets copied into a new typed array. Each value intypedArray
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 thetypedArray
argument. object
-
When called with an
object
argument, a new typed array is created as if by theTypedArray.from()
method. -
buffer
,byteOffset
,length
-
When called with a
buffer
, and optionally abyteOffset
and alength
argument, a new typed array view is created that views the specifiedArrayBuffer
. ThebyteOffset
andlength
parameters specify the memory range that will be exposed by the typed array view. If both are omitted, all ofbuffer
is viewed; if onlylength
is omitted, the remainder ofbuffer
is viewed.
Examples
Different ways to create a Float64Array
// From a length
const float64 = new Float64Array(2);
float64[0] = 42;
console.log(float64[0]); // 42
console.log(float64.length); // 2
console.log(float64.BYTES_PER_ELEMENT); // 8
// From an array
const x = new Float64Array([21, 31]);
console.log(x[1]); // 31
// From another TypedArray
const y = new Float64Array(x);
console.log(y[0]); // 21
// From an ArrayBuffer
const buffer = new ArrayBuffer(64);
const z = new Float64Array(buffer, 8, 4);
console.log(z.byteOffset); // 8
// From an iterable
const iterable = function*() { yield* [1, 2, 3]; }();
const float64FromIterable = new Float64Array(iterable);
console.log(float64FromIterable);
// Float64Array [1, 2, 3]
Specifications
Specification |
---|
ECMAScript Language Specification # sec-typedarray-constructors |
Browser compatibility
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