Comma operator to reset this

Question

In following code

var x = { f: function () { return this === window } };
(0, x.f)();

I'm using construction (0, x.f) to run function with this equal to Window (or undefined in strict mode).

But typescript says

Left side of comma operator is unused and has no side effects.

But actually there is a side effect on this of function I'm calling.

How should I write my code to eliminate this error message?

Answer 1

Zero itself really doesn't have side effects, but comma operator does.

So the possible solution is to add as any to 0:

var x = { f: function () { return this === window } };
(0 as any, x.f)();