$(document).ready(function(){
			$('#submitbtn').click(function(){
				validateForm();
				return false;
			});
		});
		
		function validateForm(){
			var data = {};
			var errors = [];
			var required = {subject:true, phone:true};
			
			$("input[type!='button'], textarea").each(function(i){
				if (isset(required[this.id]) && this.value==='') {
					errors[errors.length] = 'Missing '+this.name+'.';
				} else {
					data[this.id] = this.value;
				}
			});
			
			if (errors.length>0) {
				alert(errors.join("\n"));
				return false;
			}
			
			$.post('mail_form.php', data, function(resp){
				if (resp.error==1) {
					alert(resp.msg);
					return false;
				}
				
				$('#form').css('display', 'none');
				$('#success').css('display', 'block');
			}, 'json');
		}
		
		function isset () {
		    var a=arguments, l=a.length, i=0;
		    if (l===0) {
		        throw new Error('Empty isset'); 
		    }
		    while (i!==l) {
		        if (typeof(a[i])=='undefined' || a[i]===null) { 
		            return false; 
		        } else { 
		            i++; 
		        }
		    }
		    return true;
		}