Lift - Returning Errors and Updating Parent Div Class From Ajax Form - scala

Question

I have an ajax form which which is currently returning errors using the S.error() method. This is fine but I also want to add a new css class to one of the elements parent div tags. I have tried to do this with the JE.Call() method with no avail. Is anyone could point me in the right direction it would be really appreciated.
Snippet Code
class Register {
private var user = User.createRecord
private var pw2 = ""
private var dob = ""
private var errors = new Array[String](7)
val whence = S.referer openOr "/"
Thread.sleep(400)
def registerUser(): JsCmd = {
errors(0) = User.validateUsername(user.username.is)
errors(1) = User.validateEmail(user.email.is)
errors(2) = User.validatePhone(user.phone.is)
errors(3) = User.validateCity(user.city.is)
errors(4) = User.validateDOB(dob)
errors(5) = User.validatePassword(user.uPw.is)
errors(6) = User.validateSecondPW(user.uPw.is, pw2)
if(errors.count(_ != "") == 0) {
user.uPw.set(User.hashPassword(user.uPw.is, user.id.is.toString))
user.dob.set(User.stringToDate(dob))
user.save
println("User id " + user.id.is.toString + " added to database")
S.redirectTo(whence)
}else{
if(errors(0) != "")
S.error("username-error", errors(0))
JE.Call("addError(username-error)")
......
}
}
def form = {
"id=username" #> SHtml.text("", user.username.set(_), "placeholder" -> "Username") &
"id=email" #> SHtml.email("", user.email.set(_), "placeholder" -> "Email") &
"id=phone" #> SHtml.text("", user.phone.set(_), "placeholder" -> "Tel") &
"id=city" #> SHtml.text("", user.city.set(_), "placeholder" -> "City") &
"id=dob" #> SHtml.text("", dob = _, "placeholder" -> "DOB") &
"id=password" #> SHtml.password("", user.uPw.set(_), "placeholder" -> "Password") &
"id=passwordCheck" #> SHtml.password("", pw2 = _, "placeholder" -> "Confirm Password") &
"type=submit" #> SHtml.ajaxSubmit("Register", () => registerUser, "class" -> "btn")
}
}
HTML Template
<h2>Register</h1>
<form class="lift:form.ajax?class=form-horizontal">
<div class="lift:Register.form">
<div id="id1" class="control-group">
<label class="control-label" for="username">Username:</label>
<div class="controls">
<input id="username">
<span id="username-error" class="help-inline"></span>
</div>
</div>
<div class="controls">
<button type="submit" ></button>
</div>
</div>
</form>
Javascript Function
<script>
function addError(id) {
$("#"+id).closest(".control-group").addClass("error");
}
addError("email-error")
</script>

Answer 1

Try to change the Call function.
JE.Call("addError","username-error").cmd

Answer 2

I recommend giving up on JavaScript abstractions in Lift and use plain Run Object everywhere. So In your case I'd use:
Run("addError(username-error)")