Opening new tab/browser in Javascript

Hi does anyone know how to open a new browser (detect when using IE) or new tab (detect when using Firefox) and navigate to another website on button click?

I am trying to convert my vbscript to javascript. THis is what I had for vbscript:

 Sub Check_OnClick
  'retrieve data from current form
  Dim username : username = Document.LoginForm.username.value
  Dim password : password = Document.LoginForm.password.value
 
 
 
  'start another IE window to login
  Dim objIE : Set objIE = CreateObject("InternetExplorer.Application")
 
  objIE.Visible = True
  objIE.Navigate "file://c:/search.html"
  Do While objIE.Busy
   WScript.Sleep 500
  Loop   
  
  objIE.Document.Login.USER.value = username
  objIE.Document.Login.PASSWORD.value = password
  objIE.Document.Login.submit
 
 End Sub
 

instead of button click you could use hyperlink click: <a href="blah.html" target="_blank">Submit</a>

IE6 will open a new window. IE7 and FF will open a new tab (for both browsers this can be overridden by the user in the options)

that's a good idea.. is it possible to hide the new window, so it'll seem everything is done in the background automatically?

i need to call a javascript functino to get the entered data from the form, go to another website, fill in THAT form with the stored info

hold on a sec..is this an HTML Application or a webpage?

not sure what you mean by "html app or webpage", but I 'll be storing variables from the current form, and on the side, go to another webpage to fill in that webpage's form, with the variables I stored.
I wanted to make this process look automatic, by not showing the second website, and what' it's doing.