Using parse and javascript to find friends

Question

In my program, if people follow you back you are friends. I'm trying to get my friends. I use the following function, and it sets up the correct number of users but they're all named the same thing. Any ideas?

function getMyFriends() {

    var relation = Parse.User.current().relation("peopleIFollow");
    relation.query().find({
    success: function(results) {
        // results is an array of Parse.Object
        var myFriendsArrayTemp=[];
        while(document.getElementById("datalist").hasChildNodes() )    {
        document.getElementById("datalist").removeChild(document.getElementById("datalist").lastChild);
                }
        for (i = 0; i < results.length; i++)    {
            var user=results[i]
            // console.log(user.getUsername())
            var relation2 = user.relation("peopleIFollow");
            // console.log(relation2)
            relation2.query().find({
            success: function(theirfriends) {
                // results is an array of Parse.Object



                for (z = 0; z < theirfriends.length; z++)   {
                    var personTheyFollow=theirfriends[z];

                    if ( personTheyFollow.getUsername() == Parse.User.current().getUsername() ) {
                        myFriendsArrayTemp.push(user.getUsername())
                        console.log(user.getUsername())
                        var datalist=document.getElementById("datalist")
                        var option=document.createElement('option')
                        option.value=user.get("name");
                        datalist.appendChild(option)
                    }
                }

            }, error: function(error) {
                // error is an instance of Parse.Error.
                refreshTimedOut();

                }
            });

        }
        console.log("****")
        console.log(myFriendsArrayTemp);
        console.log("****")


    }, error: function(error) {
        // error is an instance of Parse.Error.
         refreshTimedOut();

        }
    });
}

possible duplicate of [JavaScript closure inside loops – simple practical example](http://stackoverflow.com/questions/750486/javascript-closure-inside-loops-simple-practical-example) — Artjom B., Dec 28 '14 at 13:21

score 1 · Accepted Answer · edited May 23 '17 at 12:20

Your problem is that relation2.query().find() is an asynchronous function as such the success callback does not have access to the user whose relations are being quired.

To avoid this you can use an immediately invoked function expression to explicitly pass the user to the success callback.

This answer does a great job of explaining the issue

I cant test it, but the below should work for you:

 function getMyFriends() {
    // query all the people I follow
    var relation = Parse.User.current().relation("peopleIFollow");
    relation.query().find({
    success: function(results) {

        //create an array to hold all confirmed friends
        var myFriendsArrayTemp=[];

      //clear some on page display
        while(document.getElementById("datalist").hasChildNodes() ){
            document.getElementById("datalist").removeChild(document.getElementById("datalist").lastChild);
        }

        // loop through each of the people I follow
        for (i = 0; i < results.length; i++){

            var followedUser=results[i] //use a more unique var for this than `user`
            var relation2 = followedUser.relation("peopleIFollow");
            //get all the people this user follows
            relation2.query().find({


              success: (function(followedUser) { // IIFE
                  return function(results) {

                    //loop through the people they follow to see if in in that list
                    for (z = 0; z < theirfriends.length; z++)   {

                        var personTheyFollow=theirfriends[z];
                        if ( personTheyFollow.getUsername() == Parse.User.current().getUsername() ) {
                            // im in their list, friendship confirmed set some stuff
                            myFriendsArrayTemp.push(followedUser.getUsername())
                            console.log(followedUser.getUsername())
                            var datalist=document.getElementById("datalist")
                            var option=document.createElement('option')
                            option.value=user.get("name");
                            datalist.appendChild(option)
                        }
                    }
                  }
              })(followedUser),
              error: function(error) {
                // error is an instance of Parse.Error.
                refreshTimedOut();

                }
            });

        }
        console.log("****")
        console.log(myFriendsArrayTemp);
        console.log("****")


    }, error: function(error) {
        // error is an instance of Parse.Error.
         refreshTimedOut();

        }
    });
}

personTheyFollow.getUsername() would just be my username. That's not what I want — Brent Underwood, Dec 28 '14 at 05:14
@BrentUnderwood its not really multithreading, check out http://stackoverflow.com/questions/8963209/does-async-programming-means-multi-threading — Wesley Smith, Dec 28 '14 at 22:30

Using parse and javascript to find friends

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