arrayBuffer is not an instance of ArrayBuffer

[TMTHY]

Sometimes, in some browsers (usually old ones), calling untar from GWT client, produces exception "arrayBuffer is not an instance of ArrayBuffer."

In that part of code:

function function untar(arrayBuffer) {
	if (!(arrayBuffer instanceof ArrayBuffer)) {
		throw new TypeError("arrayBuffer is not an instance of ArrayBuffer.");
        }
...
}

Object passed to untar is actually ArrayBuffer, Chrome debugger shows that is ArrayBuffer, but "instanceof ArrayBuffer" returns false. When you remove lines with the type check, everything is working fine.

May be another version on the function can be introduced (untarUnchecked), without type checking?

[Qvazar]

A better fix would be to remove the instanceof check and use 🦆 typing instead.
If it has the required methods of an ArrayBuffer, it probably is an ArrayBuffer.

[TMTHY]

Yes, duck typing would be a good solution