Pop-Up window script, how can use in other script file

[drums]

Thanks in advance for your time.
I use this code to open pop-up windows and want to learn how to use it in other .js files.
POP-UP:
function PopUp(PopUpUrl,xW,xH){
var ScreenWidth=window.screen.width;
var ScreenHeight=window.screen.height;
var movefromedge=0;
placementx=(ScreenWidth/2)-((xW)/2);
placementy=(ScreenHeight/2)-((xH+50)/2);
WinPop=window.open(PopUpUrl,"","width="+xW+",height="+xH+",toolbar=0,location=0,directories=0,status =1,scrollbars=1,menubar=0,resizable=1,left="+placementx+",top="+placementy+",screenX=" +placementx+",screenY="+placementy+",");
}
I utilize it externally; popup.js. Using as such:
<a href="javascript:PopUp('somefile.htm','300','280')">

Then I have other .js files where I would like to use it, like for the footers on most of my pages; footer.js:
document.write('<P><a href="email.htm" target="_blank">click for PC help</a>');

What I would like to have is the email.htm file in footer.js to open utilizing the pop-up code.
I imagine using php is best. I would like to continue they way I'm currently running it but am willing to learn a different way.
Thanks again!

[glenngv]

You should use the code like this, so that even if javascript is disabled, the page will still be opened.

<a href="somefile.htm" onclick="PopUp(this.href,'300','280');return false">somefile</a>

although in the footer.js, the technique will be useless since the link is generated using document.write but it's a good practice to use.

document.write('<P><a href="email.htm" onclick="PopUp(this.href,'300','280');return false">click for PC help</a>');

[drums]

OnClick issue now

Thank you very much for your help I like the approach and am going to apply it to all the pop-ups on the site. I had an onclick alert with some of the pop ups I use letting people know that pop-up stopper programs will prevent windows from opening. This is a Little League baseball site and I really have to dummy down things because of the enduser base and I'm not talking about the kids either. I really don't want to do an onload alert for that page. But maybe the onclick isn't affected as a javascript command would be in those programs?
The footer issue is what I really wanted to tackle as I want to incorporate it for the left navigation on the site and being able to have the pop-up window function is the key.
Thanks again