function serializar(formulario){

var i, j
var cadena = ""
var valor = ""

	for (i=0;i<formulario.length;i++){


		if(formulario[i].type == "checkbox"){ // checkbox
			valor = ""
			if (formulario[i].checked) valor = formulario[i].value
			cadena +=  formulario[i].name+"="+escape(valor)+"&"
		}
		else if (formulario[i].type == "radio"){ // radiobutton
	
			if (formulario[i].checked){
				valor = formulario[i].value
				cadena +=  formulario[i].name+"="+escape(valor)+"&"
			}

		}
		else // resto de tipos de campos
			cadena +=  formulario[i].name+"="+escape(formulario[i].value)+"&"
	}
	return(cadena)
}