I have parent window (opener) and child (popup)

----------                      --------------
|         |                     |            |
| parent  | -----> opens popup  |  child     |
|         |                     |            |
-----------                     --------------

Let's say, in parent page, I have js function hello()

In order for child to call parent's hello() when the child window is closed and also pass an argument, I can do,

window.close();
window.opener.hello(someArgument);

This will close the window and also call parent's hello();

But what if I don't want to have the code window.opener.hello() in child page? I mean I want the code to be in parent page only

One thing I can think of is:

Somewhat parent knows when the child is closed (event listenr??? not sure in js) But in such case how to receive the argument? (i.e. some data back from the child)