Be kind its fast

Just a simple question : what did i need to put on value ?
(google devtools say : Uncaught TypeError: Cannot set properties of null (setting 'value') )

var addr = window.location.href; //recuperation de URL de la page
var param = addr.split('?')[1]; //decoupe URL après le ?
var rep=new URLSearchParams(param);//transforme en dico parametre:valeur
console.log(rep.get("reponse")); //affichage de la valeur associer a id/name reponse
document.getElementById("Votre Pseudo:").value=rep.get("???");

ty for help