Why is my function not returning the array?

Question

This is my code:

document.getElementById('revealUser').onclick = displayDaUsers

function displayDaUsers(){
  pullAllUsersFromDB();
  debugger;
}


function pullAllUsersFromDB(){
  rootRef.child('users').on('value', function(snapshot) {
    var users_array = [];
    var users_object = snapshot.val();
    Object.keys(users_object).map(function(key) {
      users_array.push(users_object[key]);
    });
    // window.dateApp.allUsers = users_array;
    return users_array
  });
}

html:

<input type="submit" id="revealUser" value="reveal user">

I put a debugger in to see the problem but it does not help. When I go into the console and type in users_array I get Uncaught ReferenceError: users_array is not defined(…)

NEW CODE (EDIT):

according to another stackoverflow answers this should work..

function displayDaUsers(){
  var test = pullAllUsersFromDB();
  console.log(test);
  //pullAllUsersFromDB();
  //debugger;
  //setUpFirstUser()
}


function pullAllUsersFromDB(){
  rootRef.child('users').on('value', function(snapshot) {
    var users_array = [];
    var users_object = snapshot.val();
    Object.keys(users_object).map(function(key) {
      users_array.push(users_object[key]);
    });
    //window.dateApp.allUsers = users_array;
    return users_array
  });
}

it's declared inside a function (local scope). so it's not accessible from console — Madhawa Priyashantha, Sep 12 '16 at 18:41
`users_array` is a local variable, and you never catch the return value of the function call. — Jean-Baptiste Yunès, Sep 12 '16 at 18:44
but I put a debugger in, which means I have access inside that function? @FastSnail — Waterman1, Sep 12 '16 at 18:47
so why is not accessible or rather, how can I make it accessible? — Waterman1, Sep 12 '16 at 18:52

score 0 · Answer 1 · answered Sep 12 '16 at 18:43

0

The return value users_array is local to the scope of the anonymous callback function function(snapshot) {.... In other words, its value is lost outside of that scope.

At what point in your logic do you need access to user_array? If you need access to it outside of the context of your functions, maybe it makes sense to define a variable with greater scope, and then setting its value in your anonymous function. E.g.

document.getElementById...
var arr;

...

function pullAllUsersFromDB() {
    ...
    ...function(snapshot) {
        arr = users_array;
    });
}

// pullAllUsersFromDB() (and its callback) must be called for arr to be defined at this point in execution

answered Sep 12 '16 at 18:43

I need it to be accessible to the other method `displayDaUsers`. is that not possible? – Waterman1 Sep 12 '16 at 18:46
If that is the case then it makes sense to pass in `users_array` as a callback value that `displayDaUsers` can access. So, `pullAllUsersFromDB` should be augmented with a callback parameter. – Sep 12 '16 at 18:48
so how would that look? what argument would `pullAllUsersFromDB` take and what would it look like inside the other function? (i'm not asking you to do it for me, just need to learn how this type of scoping works) – Waterman1 Sep 12 '16 at 18:52
edited now dude – Waterman1 Sep 12 '16 at 19:21
Please see the answers to the duplicate question: http://stackoverflow.com/questions/14220321/how-do-i-return-the-response-from-an-asynchronous-call – Sep 12 '16 at 20:17

Why is my function not returning the array?

1 Answers1