var formElement;
$(document).ready(function() { 
    var options = { 
        target:        '#cad_news_return',   // target element(s) to be updated with server response 
        beforeSubmit:  showRequest,  // pre-submit callback 
        success:       showResponse,  // post-submit callback 
        clearForm: true        // clear all form fields after successful submit 
     }; 
    $('#cad_news_form').ajaxForm(options); 
}); 
 
function showRequest(formData, jqForm, options) {
	formElement = jqForm[0]; 
	formElement.bt_submit.disabled = true;
	 
	if (formElement.stNome.value == "") {
		$('#cad_news_return').html('Nome obrigatório');
		formElement.bt_submit.disabled = false;
		return false;
	}
	 
	if (formElement.stEmail.value == "") {
		$('#cad_news_return').html('E-mail obrigatório');
		formElement.bt_submit.disabled = false;
		return false;
	} else {
		if (!validaEmail(formElement.stEmail.value)) {
			$('#cad_news_return').html('E-mail em formato inválido');
			formElement.bt_submit.disabled = false;
			return false;
		} 
	}
	
	return true; 
} 
 
// post-submit callback 
function showResponse(responseText, statusText)  {
	formElement.bt_submit.disabled = false; 
}

function validaEmail(email) {
	var reg = /^([A-Za-z0-9_\-\.])+\@([A-Za-z0-9_\-\.])+\.([A-Za-z]{2,4})$/;
	if (reg.test(email) == false)
		return false;
	else
		return true;
}