Getting Firebase error when writing a variable to a path

Question

I'm grabbing a URL and parsing it to create a variable called list. I have this variable printing in the console inside and outside of the function. I also have tried grabbing the URL again inside of the function. Firing this function gives me an error of:

Reference.update failed: First argument must be an object containing the children to replace.

How can I pass the correct variables to the function so that I can write to Firebase?

The JS is:

var getQueryString = function ( field, url ) {
    var href = url ? url : window.location.href;
    var reg = new RegExp( '[?&]' + field + '=([^&#]*)', 'i' );
    var string = reg.exec(href);
    return string ? string[1] : null;
};

var list = getQueryString('list', window.location.href);
console.log(list);
document.getElementById('list').innerText = list;

function accept(){
  var list = getQueryString('list', window.location.href);
  console.log("accept", "list", list);
  var user = firebase.auth().currentUser;
  var uid = user.uid;
  console.log("accept", "uid", uid);
  firebase.database().ref('userprofile/' + uid +  '/list').update(list);
  return firebase.database().ref('userlists/' + list +  '/members/' + uid).update('true');
}

Answer 1

What you're doing now is equivalent to a set() operation:

return firebase.database().ref('userlists/' + list +  '/members/' + uid).set('true');

Alternatively you can perform the update one level higher:

var updates = {};
updates[uid] = 'true';
return firebase.database().ref('userlists/' + list +  '/members/' + ).update(updates);