IF "something" contains "something"?

[AlphaWolf]

Hi,

I'm trying to make something that changes a web page back and forth. I'd like to to check what the domain already has in it, so it can change it correctly. I'm currently using

 

	if (myVolume == '.co.uk') {		event.target.browserWindow.activeTab.url = currentURL.replace(/\.com/ig, ".co.uk");}

 

 

I'd like this to check "currentURL", and IF it contains .co.uk, then replace with .com, if it contains .com, then changes it to .co.uk.

I think I'm missing something simple here, but I can't figure it out 

Thanks,

Joseph Duffy