Validacion JS

[MMCQ]

<script type="text/javascript">

function user(){
//usuario
if (document.form1.username.value.length<4){
divuser.innerHTML="TunerSpot ID Must Have Least 4 Chars";
document.form.username.focus()
return 0;
}else{

if(document.form1.username.value==""){
divuser.innerHTML="Este campo es requerido";
document.form.username.focus()

}
}
}

function validar(){

if (document.form1.field.value==""){
divgeneral.innerHTML="Este campo es requerido";


}
}
function select(){
if (document.form1.field.selectedIndex==0){
divuser.innerHTML="Este campo es requerido";

}
}

function checkMail()
{
var x = document.form1.email.value;
var filter = /^([a-zA-Z0-9_\.\-])+\@(([a-zA-Z0-9\-])+\.)+([a-zA-Z0-9]{2,4})+$/;
if (filter.test(x)) ;
else divemail.innerHTML="Incorrent Email Adress";;
}

</script>