<script type="text/javascript">
function checkField(val) {
	if(document.getElementById(val).value == "") {
		document.getElementById(val).style.border = "1px solid red";
	} else  {
		document.getElementById(val).style.border = "";
	}
}
</script>
<input type="text" name="name" id="name" onblur="checkField(this.id)"  />
<input type="text" name="email" id="email" onblur="checkField(this.id)"/>

<script type="text/javascript">
function checkField(val) {
	if(document.getElementById(val).value == "") {
		document.getElementById(val).style.border = "1px solid red";
	} else  {
		document.getElementById(val).style.border = "";
	}
}
function SendForm() {
var err = "";
if (document.getElementById("name").value == "") {
	document.getElementById("name").style.border = "1px solid red";
        err = 1;
    }

if (document.getElementById("email").value == "") {
	document.getElementById("email").style.border = "1px solid red";
	err = 1;
    }
if(err) {
	return false;
}
return true;

}
</script>
<form action="aa.php" method="post" onsubmit="return SendForm();">
<input type="text" name="name" id="name" onblur="checkField(this.id)"  />
<input type="text" name="email" id="email" onblur="checkField(this.id)"/>
<input type="submit" name="submit"/>
</form>