Include no path information at all, just like in a link:

window.location.replace("page2.aspx");

Here's a live example The example switches between

http://jsbin.com/asupup/2   -- The 2 corresponds to your page1.aspx

...and

http://jsbin.com/asupup/3   -- The 3 corresponds to your page2.aspx

...and so the 2 page uses

window.location.replace("3");

...and the 3 page uses

window.location.replace("2");

For more about how URLs (and in particular relative URLs) work, see RFC3986. But basically:

• If a relative URL doesn't start with . or /, it replaces the last segment. So:

  
  

      http://foo.com/one/two/page.html
  
    + bar.html
  
    = http://foo.com/one/two/bar.html
  
  

  
  



• If a relative URL starts with ../, it replaces the last segment and the one above it:

  
  

      http://foo.com/one/two/page.html
  
    + ../bar.html
  
    = http://foo.com/one/bar.html
  
  

  
  

  Note that the two subfolder has been replaced. Multiple ../s can be used to move up multiple levels:

  
  

      http://foo.com/one/two/three/four/page.html
  
    + ../../bar.html
  
    = http://foo.com/one/two/bar.html
  
  

  
  



• If a relative URL starts with a single /, it replaces everything after the hostname (and port, if any). So:

  
  

      http://foo.com/one/two/page.html
  
    + /bar.html
  
    = http://foo.com/bar.html
  
  
  
      http://foo.com:8080/one/two/page.html
  
    + /bar.html
  
    = http://foo.com:8080/bar.html
  
  

  
  



• If a relative URL starts with //, it replaces everything following the protocol, so:

  
  

      http://ex.com/folder/page.html
  
    + //foo.com
  
    = http://foo.com
  
  

  
  

  (This is handy when loading resources and you want to avoid worrying about http vs. https and mixed-content warnings.)