DataView.prototype.byteLength

The byteLength accessor property of DataView instances returns the length (in bytes) of this view.

The byteLength property is an accessor property whose set accessor function is undefined, meaning that you can only read this property. If the DataView is length-tracking, then its length depends on the length of the underlying buffer, and may change if the buffer is resized. Otherwise, the value is established when the DataView is constructed and cannot be changed. Whether length-tracking or not, the byteLength becomes 0 if the underlying buffer is resized such that the viewed range is no longer valid.