files/en-us/web/javascript/reference/global_objects/dataview/setfloat64/index.md

metadata

title: DataView.prototype.setFloat64()
short-title: setFloat64()
slug: Web/JavaScript/Reference/Global_Objects/DataView/setFloat64
page-type: javascript-instance-method
browser-compat: javascript.builtins.DataView.setFloat64
sidebar: jsref

The setFloat64() method of {{jsxref("DataView")}} instances takes a number and stores it as a 64-bit floating point number in the 8 bytes starting at the specified byte offset of this DataView. There is no alignment constraint; multi-byte values may be stored at any offset within bounds.

{{InteractiveExample("JavaScript Demo: DataView.prototype.setFloat64()")}}

// Create an ArrayBuffer with a size in bytes
const buffer = new ArrayBuffer(16);

const view = new DataView(buffer);
view.setFloat64(1, Math.PI);

console.log(view.getFloat64(1));
// Expected output: 3.141592653589793

Syntax

setFloat64(byteOffset, value)
setFloat64(byteOffset, value, littleEndian)

Parameters

• byteOffset
  • : The offset, in bytes, from the start of the view to store the data in.
• value
  • : The value to set. For how the value is encoded in bytes, see Value encoding and normalization.
• littleEndian {{optional_inline}}
  • : Indicates whether the data is stored in little- or big-endian format. If false or undefined, a big-endian value is written.

Return value

{{jsxref("undefined")}}.

Exceptions

• {{jsxref("RangeError")}}
  • : Thrown if the byteOffset is set such that it would store beyond the end of the view.

Examples

Using setFloat64()

const buffer = new ArrayBuffer(10);
const dataview = new DataView(buffer);
dataview.setFloat64(0, 3);
dataview.getFloat64(1); // 3.785766995733679e-270

Specifications

{{Specifications}}

Browser compatibility

{{Compat}}

See also

• JavaScript typed arrays guide
• {{jsxref("DataView")}}
• {{jsxref("ArrayBuffer")}}
• {{jsxref("Float64Array")}}