Javascript up arrow keypress not firing

Question

I've been doing some JS recently and getting this stupid error, I can detect the return key using e.keyCode and checking for keyCode == 13 but when I try to check for 38 (Up arrow) it never fires. Any help please?

HTML:

<input type="text" id="TxtMessage" 
       placeholder="Message" onKeyPress="SendMsg(event)" >

Javascript:

function SendMsg(e)
{
var message = document.getElementById("TxtMessage");

if(e.keyCode ==13)
{
    var json = {"message": message.value};
    json = JSON.stringify(json);
    ws.send(json);
    PreviousMessage = message.value;
    message.value = "";
    message.focus();
}
else if(e.keyCode == 38) 
{ 
    message.value = PreviousMessage;
}
}

EDIT: Fixed by changing onKeyPress to onKeyDown... Strange.

Answer 1

Replace your following lines:

if(e.keyCode !=13) return;
if(e.keyCode == 38) { message.value = PreviousMessage; return;  }

for this one:

var charCode = typeof e.which == "number" ? e.which : e.keyCode;

if(charCode == 38) { message.value = PreviousMessage; return;  }
if(charCode !=13) return;

UPDATE:
My above code still didn't work when used in keypress event, as the correct solution is to use keydown or keyup events to catch the arrow keys. See here for an enhanced answer https://stackoverflow.com/a/2218915/352672 Also see here a working jsfiddle using the keyup event.