var players = 0;

while (players < 1 || players > 2)
  players = prompt("Enter number of players (1 or 2)", 1);
  
if (players == 2) alert("Choose your partner!");

---

confirm
 Displays a Confirm dialog box with the specified message and OK and Cancel buttons


Method of
 window
 
Implemented in
 JavaScript 1.0
 


Syntax 

confirm(message)

Parameters 

message
 A string.

Examples

This example uses the confirm method in the confirmCleanUp function to confirm that the user of an application really wants to quit. If the user chooses OK, the custom cleanUp function closes the application.

function confirmCleanUp() {
   if (confirm("Are you sure you want to quit this application?")) {
      cleanUp()   }
}


another example

function confirm_url (message, next_url) {
	confirm_result = confirm(message);
	if (confirm_result == true) {
		document.location = next_url;
		return true;
	} else { }
}


See also 
window.alert, window.prompt