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Float64Array.float64Array

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 [, byteOffset [, length]]);

Parameters

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.
typedArray
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.
object
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.

Examples

Different ways to create a Float64Array

// From a length
var 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
var arr = new Float64Array([21,31]);
console.log(arr[1]); // 31

// From another TypedArray
var x = new Float64Array([21, 31]);
var y = new Float64Array(x);
console.log(y[0]); // 21

// From an ArrayBuffer
var buffer = new ArrayBuffer(32);
var z = new Float64Array(buffer, 0, 4);

// From an iterable 
var iterable = function*(){ yield* [1,2,3]; }();
var float64 = new Float64Array(iterable);
// Float64Array[1, 2, 3]

Specifications

Browser compatibilityUpdate compatibility data on GitHub

Desktop
Chrome Edge Firefox Internet Explorer Opera Safari
Float64Array() constructor 7 12 4 10 11.6 5.1
Constructor without arguments 7 12 55 10 11.6 5.1
new Float64Array(iterable) 39 14 52 No 26 10
Float64Array() without new throws 7 14 44 No 15 5.1
Mobile
Android webview Chrome for Android Firefox for Android Opera for Android Safari on iOS Samsung Internet
Float64Array() constructor 4 18 4 12 4.2 1.0
Constructor without arguments ≤37 18 55 12 5 1.0
new Float64Array(iterable) 39 39 52 26 10 4.0
Float64Array() without new throws ≤37 18 44 14 5 1.0
Server
Node.js
Float64Array() constructor 0.10
Constructor without arguments 0.10
new Float64Array(iterable) 4.0.0
Float64Array() without new throws 0.12

Compatibility notes

Starting with ECMAScript 2015, Float64Array constructors require to be constructed with a new operator. Calling a Float64Array constructor as a function without new, will throw a TypeError from now on.

var dv = Float64Array([1, 2, 3]);
// TypeError: calling a builtin Float64Array constructor
// without new is forbidden
var dv = new Float64Array([1, 2, 3]);

See also

© 2005–2018 Mozilla Developer Network and individual contributors.
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://wiki.developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Float64Array/Float64Array