how to show an error message as invalid in login page

Question

how to show invalid username after entered username..when cursor is in password without any button Login Form UserId : Password :

yadagiri uppari · Answer

just tell me where i need to add........that event(piece of code)

yadagiri uppari · Answer

please send me piece of code and whete i need to add code: function check(f) { var b=f.T2.value; //var a=f.t7.value; if(b.length { alert(Password should have six cahractors); return false; } if(f.id.value==''){ alert(Please enter Id); return false; } else if(f.T2.value==''){ alert(Please enter Password); return false; } else { return true; } } Login Form UserId : Password :

Sanjeeb Lenka · Answer

on userid textbox you have to raise the textchanged event of that text box and within that textchanged event you have to check the username from database. if you want more information reply