Question

Is it possible to copy a function (or any object for that matter) from one window context to another in Javascript?

Let’s say I have a parent window with a frame in it. The frame defines a function foo(), which I’d like to copy to the outer window. (One reason to do it would be so that foo() is available when the frame document navigates to a different URL.)

I know I can easily create a reference to foo() in the parent by doing

function foo() { ... }     parent.foo = foo; 

But with this method foo() still lives in the frame document, and will not be available to the parent should frame get unloaded.

I know I can also create a new function in the parent by using the Function constructor:

parent.foo = new parent.Function(' ... '); 

However, this requires me to have my function as a JS string.

DOM supports moving nodes from one document to another via importNode(). Does Javascript have a similar feature?

Answer 1

nitko’s solution seems to be correct, though a little more work is required. This function seems to work on FF2, FF3, IE7 and Chrome:

  function importFunction(fn, win) {     var code = fn.toString();     var params = code.match(/\(([^)]*)\)/);     if (typeof(params[1]) !== 'undefined') {       params = params[1].split(/\s*,\s*/);     } else {       params = null;     }     code = code.replace(/^[^{]*{/, '');     code = code.replace(/}$/, '');     if (params) {       return new win.Function(params, code);     }      return new win.Function(code);   } 

The returned function can be used in the needed window. Something like:

parent.foo = importFunction(foo, parent);