The problem is that you are passing a loose reference to the reload function; therefore, losing its binding to window.location.

You can use the following to prove the point (It may not work

setTimeout(window.location.reload.bind(window.location), 1000)

But I think adding a function wrapper makes it easier to understand.

Example

const a = {
  value: 2,
  b: function() {
    console.log(this.value);
  }
}

a.b();

const b = a.b;
b();

const boundB = b.bind(a);
boundB();

Summary Using syntax like a.b() makes sure that b is called with a as its this.

Calling a function without a . before will the function as a global, which will pass window as this in sloppy mode and null as this in strict mode.

This can always be overriden by binding function or by using arrow functions (which take its this from the surrounding this) or if you bind your function ahead of time.

It won't work as the scope of calling window.location.reload will be window instead of window.location. Try this:

window.location.reload.call(window);

vs.

window.location.reload.call(window.location);

This post sums it up nicely https://stackoverflow.com/a/10840058/10853009

Because reload() needs window.location as this. In other words - it is a method of window.location. When you say:

var fun = window.location.reload;

fun();

You are calling reload() function without any this reference (or with implicit window reference).