Accept Only Alphabets In Text-Box

This is example used to validate a textbox which contain a alphabets.
Javascript

function AllowAlphabet(e)
 {
 isIE=document.all? 1:0 keyEntry = !isIE? e.which:event.keyCode;
 if (String.fromCharCode(keyEntry).match(/^[a-zA-Z]+$/) || keyEntry == 8 || keyEntry == 32 || keyEntry == 0)
{ return true;
 } else
{ return false; }
 }

Html Code:

<input type="text" id="txtemail"  onkeypress="return AllowAlphabet(event)" />
 
Demo: