How would I repeat a block of code in Javascript? (asking users for a username and password) -

i want have repeat function around bit of javascript code:

<script language="javascript">      var usernamecheck="username";     var passcheck="password";      var username=prompt ('enter username',' ');     var password=prompt ('enter password',' ');     if          (username+password==usernamecheck+passcheck) ;     else         {window.location="http://www.google.com";}  </script> 

i want bit of code repeat 3 times if user inputs incorrect username or password in.

i want inform user password or username have entered incorrect , tell them try again. when have had 3 tries sent webpage e.g."http://www.google.com" .

how this? (please help)

can't use loop?

for example:

<script language="javascript">  var usernamecheck="username"; var passcheck="password";  var username=prompt ('enter username',' '); var password=prompt ('enter password',' ');  //create counter var var counter = 3;  //next create loop loop 3 times if still credidentials //are incorrect send user google.com (var = 0; < counter; i++){     if {       (username+password==usernamecheck+passcheck) ;       //put in code terminate loop     }     else       var username=prompt ('enter username',' ');       var password=prompt ('enter password',' ');} }  window.location="http://www.google.com"; </script> 

i agree else not means of site protections, not familiar javascript language (i program in java) seems familiar enough.

also check logic else stated above