The byteLength accessor property represents the length (in bytes) of the dataview.


The byteLength property is an accessor property whose set accessor function is undefined, meaning that you can only read this property. The value is established when an DataView is constructed and cannot be changed. If the DataView is not specifying an offset or a byteLength, the byteLength of the referenced ArrayBuffer or SharedArrayBuffer will be returned.


Using the byteLength property

var buffer = new ArrayBuffer(8);
var dataview = new DataView(buffer);
dataview.byteLength; // 8 (matches the byteLength of the buffer)

var dataview2 = new DataView(buffer, 1, 5);
dataview2.byteLength; // 5 (as specified when constructing the DataView)

var dataview3 = new DataView(buffer, 2);
dataview3.byteLength; // 6 (due to the offset of the constructed DataView)


ECMAScript Language Specification (ECMAScript)
# sec-get-dataview.prototype.bytelength

Browser compatibility

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See also