How do I update data in indexedDB?

Question

I have tried to get some information from W3C regarding the update of an objectStore item in a indexedDB database, but with not so much susccess. I found here a way to do it, bu

Answer 1

this is case of update infos of an user object

var transaction = db.transaction(["tab_user"], "readwrite");
var store = transaction.objectStore("tab_user");

var req = store.openCursor();
req.onerror = function(event) {
  console.log("case if have an error");
};

req.onsuccess = function(event) {
    var cursor = event.target.result;
    if(cursor){
        if(cursor.value.idUser == users.idUser){//we find by id an user we want to update
            var user = {};
            user.idUser = users.idUser ;
            user.nom = users.nom ;

            var res = cursor.update(user);
            res.onsuccess = function(e){
                console.log("update success!!");
            }
            res.onerror = function(e){
                console.log("update failed!!");
            }
        }
        cursor.continue();
    }
    else{
        console.log("fin mise a jour");
    }
}