Question

this function gets a question from a database and is supposed to return it.
The database is a Parse object(https://www.parse.com/docs/js_guide). As indicated in the comments in the code the question is accessible from within the success function of the db call but not from outside it and simply putting the return statement inside the success block doesn’t work either.
Code below. Any suggestions?

function getQuest(){

    var Question = Parse.Object.extend("Question");
    var query = new Parse.Query("Question");
    var questlist = [];
    var newquestion;
    //get list of questions if chosen track is python or java. track is set globally

    if (track == "python")
    {

        query.equalTo("track", "xstsysysus7");

    } else if (track == "java"){

        query.equalTo("track", "XAWqBgxFAP");

    }

    query.find({

        success: function(questions){
        // return list of questions
            var i = Math.floor(Math.random()*10);
            newquestion = questions[i].get('question');
             console.log(newquestion); // works here

    },

        error: function(error){
            console.log(error.message);
        }


    });

    console.log(newquestion); //returns undefined here
    return newquestion;

}

Answer 1

You cannot return from the callback method like this, this is an async issue, you should use a callback method to get your variable out from the method

function getQuest(callback){

var Question = Parse.Object.extend("Question");
var query = new Parse.Query("Question");
var questlist = [];
var newquestion;
//get list of questions if chosen track is python or java. track is set globally

if (track == "python")
{

    query.equalTo("track", "xstsysysus7");

} else if (track == "java"){

    query.equalTo("track", "XAWqBgxFAP");

}

query.find({

    success: function(questions){
    // return list of questions
        var i = Math.floor(Math.random()*10);
        newquestion = questions[i].get('question');
        //call the callback method here and pass your variable as a param
        if(callback != null && callback != undefined){
              callback(newquestion);
        }


},

    error: function(error){
        console.log(error.message);
    }


});

}

Now you can call your getQuest method just like this instead of using var newQ = getQuest()

getQuest(function(newQuestion){
   // do your stuff with newQuestion 
})