Putting an object into an array in JavaScript

Question

I'm currently working with an MVC JS framework and I want to be able to get a list of objects that I can take a random entry out of on a loop. So far I've managed to create a function that finds a random ID and pulls out that object so that part is not a problem. It's what is going into the array of objects:

QuestionsSetup: function(gameType) {

        // Setup Resources
        var c = this.View.children;
        var player1qs = [];
        var leftQ = 0;
        var rightQ = 0;
        var maxQValue = 50;
        var minQValue = 1;

        // Fill array with questions 
        for (var i = 0; i < 5; i++) {

            // Build a random question with numbers between 1 and 50

            // Build Question Text to output to user

            // Generate correct answers based on generated question

            // Generate unsorted, incorrect answers and add them to an array

            //Place Questions into object
            questions.qId = i;
            questions.leftQ = leftQ;
            questions.rightQ = rightQ;
            questions.correctAnswer = correctAnswer;
            questions.allAnswers = sortedAnswers;
            questions.questionText = questionText;

            //Add to array of questions
            player1qs.push(questions);
        }
    }

This does add them to an array but when adding a new object it also changes the values of the existing objects in the array so they all come out the same no matter which one I pull out later. The questions object is declared in it's own file in a models folder. Is there any way, at the start of each loop, to tell the application I want new empty questions object as opposed to referencing the existing ones? I know that you can in similar back end languguages so I refuse to beleive that something so simple doesn't exist in JavaScript too?

There's way too much code, try to come with a minimal example please — Axnyff
– Axnyff, Commented Jan 25, 2017 at 10:40
Its passing by reference, so updating the original data is updating the original referenced data. You should use a new questions object each time? — Brian Ramsey
– Brian Ramsey, Commented Jan 25, 2017 at 10:44
where is you 'questions' defined? is it in global space? you overwrite the properties with every iteration and push to array always the same object. — webduvet
– webduvet, Commented Jan 25, 2017 at 10:45

pttsky · Accepted Answer · 2017-01-25 10:46:48Z

1

Declaring a variable for each array item is definitely missing.

QuestionsSetup: function(gameType) {

    // Setup Resources
    var c = this.View.children;
    var player1qs = [];
    var leftQ = 0;
    var rightQ = 0;
    var maxQValue = 50;
    var minQValue = 1;

    // Fill array with questions 
    for (var i = 0; i < 5; i++) {

        var tempQuestion = {
           qId: i,
           leftQ: leftQ,
           rightQ: rightQ,
           correctAnswer: correctAnswer,
           allAnswers: sortedAnswers,
           questionText: questionText
        }


        // ...


        //Add to array of questions
        player1qs.push(tempQuestion);
    }
}

Using a separate closure inside a loop also might be a good idea.

answered Jan 25, 2017 at 10:46

pttsky

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webduvet · Accepted Answer · 2017-01-25 10:47:28Z

0

do this:

for (var i = 0; i < 5; i++) {
   let questions = {};
   // the rest....

you need to define the object first.

answered Jan 25, 2017 at 10:47

webduvet

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mgajic · Accepted Answer · 2017-01-25 10:50:08Z

0

Maybe you should just initialize the questions object before initializing its properties, so the code should look like this:

       //Place Questions into object
        questions = {};

        questions.qId = i;
        questions.leftQ = leftQ;
        questions.rightQ = rightQ;
        questions.correctAnswer = correctAnswer;
        questions.allAnswers = sortedAnswers;
        questions.questionText = questionText;

        //Add to array of questions
        player1qs.push(questions);

answered Jan 25, 2017 at 10:50

mgajic

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