Question

I have this simple function

function Login()
{
var x=prompt("Please enter your name","");
var xmlhttp;
if (window.XMLHttpRequest)
  {// Използваните браузъри
  xmlhttp=new XMLHttpRequest();
  }
else
  {// Кой ли ползва тези версии..
  xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
  }
    xmlhttp.open("GET","login.php?u="+x,true);
    xmlhttp.send();
    }

The problem is when the user decide to exit the prompt box by clicking ESC.Can someone explain to me what exactly happen with the variable x in this case.I get to the conclusion that it get assignied with the value ‘null’ and by null I mean a string, because when I check with

If(!is_null($u))

my script doesn’t work, but if I replace this with

If($u!='null')

then everything works just fine, so could someone explain me what in fact is happening with the prompt box value when you exit it with pressin ESC?

Answer 1

It returns as if you had clicked cancel.

It is null not as a string ..

alert( prompt('') === null );

will alert true if you press Esc or cancel button