function validaForm(objFrm){
		if (document.getElementById('txt_nombrecont')){		
			if(document.getElementById('txt_nombrecont').value.length ==0 || document.getElementById('txt_nombrecont').value.length == ""){
				alert('Ingrese Nombre');
				document.getElementById('txt_nombrecont').focus();
				return false;
			}
		}//end if
		if (document.getElementById('txt_apellidocont')){		
			if(document.getElementById('txt_apellidocont').value.length ==0 || document.getElementById('txt_apellidocont').value.length == ""){
				alert('Ingrese Apellido');
				document.getElementById('txt_apellidocont').focus();
				return false;
			}
		}//end if
		
		if (document.getElementById('txt_telefonocont')){		
			if(document.getElementById('txt_telefonocont').value.length ==0 || document.getElementById('txt_telefonocont').value.length == ""){
				alert('Ingrese Telefono');
				document.getElementById('txt_telefonocont').focus();
				return false;
			}
		}//end if
		
		if (document.getElementById('txt_emailcont')){				
			if(document.getElementById('txt_emailcont').value.length ==0 || document.getElementById('txt_emailcont').value.length == ""){
				alert('Ingrese Email');
				document.getElementById('txt_emailcont').focus();
				return false;
			}else{
				if(!email_valido(document.getElementById('txt_emailcont'))){
					document.getElementById('txt_emailcont').focus();
					return false;
				}
			}	
		}//end if
		
		if (document.getElementById('txt_comentcont')){				
			if(document.getElementById('txt_comentcont').value.length ==0 || document.getElementById('txt_comentcont').value.length == ""){
				alert('Ingrese un comentario');
				document.getElementById('txt_comentcont').focus();
				return false;
			}//end if
		}//end if		
		
		objFrm.submit();
	}//end function validaForm
	
	function email_valido(texto){
		var txt = texto.value;
		//expresion regular
		var b=/^[^@\s]+@[^@\.\s]+(\.[^@\.\s]+)+$/
			
		if(!b.test(txt)){
			alert("Email no válido.");		
			return false;
		}  
		return true;
	}//end fucntion email_valido