Can't pass a function from one window to another in IE

Question

I have a two windows, one is opened from another, so, I have an `opener` property in "child" window. Parent window has some function in global scope, which must be called with a function as a first argument (it will be used as a callback). Both pages are opened from same domain, so, I haven't any Same Origin Policy restrictions (I hope so)... In a child window I have code like this ``` if(window.opener) { window.opener.myFunction(function() { ... }); } ``` Everything works fine, until I try to run it in IE. In this browser an argument, received by `myFunction`, is ALWAYS of type `Object` (checked with `typeof`). Code of `myFunction` is something like this: ``` window.myFunction = function(cb) { alert('Callback type is ' + (typeof cb)); if(typeof cb == 'function') cb(); else alert('Not a function!'); } ``` Live demo: http://elifantiev.ru/ie-opener-issue/first.html The questions is: - is this a standarts compliant behaviour? - is there some workaround for this issue?

Accepted Answer

Even though typeof returns "object" the function still works as expected. Calling `cb()` will execute the function.

An alternative to using `typeof` to determine if the parameter is a function is testing for the call property which all functions are expected to have:

```
if (cb && cb.call) { cb(); }
```

If you are passing along to something that expects a function it can be wrapped like this:

```
function newCb() {
    return cb.apply(object, arguments);
}
```

Also note when passing a function from parent to the child the typeof is also object. Comparing original function to function-as-an-object (after the round trip) returns true. This is important if for some reason you need a reference to the original function (for example when unsubscribing).

Can't pass a function from one window to another in IE

Solution

Problem