Re: variable assignment from child window

[Frank Hecker <hecker@netscape.com>]

John Ray wrote:
> I need to find out if something I'm doinging is considered an
> acceptable JavaScript coding practice.

Based on my understanding of the problem, it's an acceptable coding 
practice that (absent a workaround) can unfortunately run afoul of bugs 
in the implementation.

> I've set up user registration for my home page that takes input on a
> form in a child window called stat_window. Before opening the window I
> create a property of stat_window called nav for accessing the main
> Navigator window functions and properties with:
> 
> stat_window.nav=self;
> 
> So far so good. The problem is this: From the child window I call
> a function in the nav window that needs to access the data that was
> just entered in the child window form. I don't want to change the
> function to accept arguments and pass the values unless absolutely
> necessary. What I have done is changed the values of two global
> variables (user_name and e_mail) in the Navigator window, from the
> child window with the following.
> 
> nav.user_name=<value from the form field>
> nav.e_mail=<value from the form field>[omitted]
> Is it legitimate to directly assign a value to a variable in a
> different window/file in this manner?

Yes; as far as I'm aware we don't deprecate this practice as inherently 
wrong.

> And if it is, is there a trick to making
> it reliable.

Try forcing a copy of the variables instead of direct assignment; e.g.,

  nav.user_name= "" + <value from the form field>

The bugs I've seen and heard of have to do with the original object in 
the child window (or frame) going away (e.g., due to a reload) and the 
parent window or frame being left with a pointer to nowhere.  Forcing a 
copy ensures that the parent window has valid values no matter what 
happens to the child window.

Frank

-- 
Frank Hecker          Pre-sales tech support, Netscape Federal sales
hecker@netscape.com   http://home.netscape.com/people/hecker/

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