create JSON object from another JSON object

Question

I don't know if the title is the right one for what I want to do.

I have the following array of objects

    array([0]: {category: "10",
                question: "101"},
          [1]: {category: "10",
                question: "102"},
          [2]: {category: "20",
                question: "201"}
    );

And I want to group all the elements into something like this:

    array([0]: {category: "10", {question: "101",
                                 question: "102"}},
                category: "20", {question: "201"}});

I don't know if this is possible or if there's another better way to solve this problem (maybe with a two-dimensional array?) but any help would be very appreciated.

Thanks!

Sorry for the lack of information, here is how I create my array of objects:

    var arr_sections = [];
    var arr_questions = [];
var jsonObj = [];
$('.ui-sortable-nostyle').each(function(){
    arr_sections.push($(this).attr("sec_id"));              
});

// create json object with pairs category - question 
$(".sortable2").each(function(i){                           
    $(this).children().each(function(j){    
        var cat = arr_sections[i];
        jsonObj.push({
            category: arr_sections[i],
            question: $(this).attr("ques_id")
        });     
    });
});  

And got an array of objects with the following structure:

    [Object, Object, Object, Object, Object]
    0: Object
       category: "1052"
       question: "3701"
       __proto__: Object 
    1: Object
       category: "1053"
       question: "3702"
       __proto__: Object
    2: Object
       category: "483"
       question: "1550"
       __proto__: Object
    3: Object
       category: "483"
       question: "1548"
       __proto__: Object
    4: Object
       category: "483"
       question: "1549"
       __proto__: Object
    length: 5

Tried to create my new array:

    for(var i = 0; i < jsonObj.length; i++){
        temp[jsonObj[i].category] = jsonObj[i].question;
}

But I don't get all values:

    [483: "1549", 1052: "3701", 1053: "3702"] 

Answer 1

You have:

var arr = [ 
  {category: "10", question: "101"},
  {category: "10", question: "102"},  
  {category: "20", question: "201"}
];

You want (i suppose):

var arrRequired = [
  {category: "10", question : ["101", "102"] },
  {category: "20", question : ["201"] }
];

I will give you:

var obj = {
  "10" : ["101", "102"],
  "20" : ["201"]
};

To convert what you have to what i will give you, you can do:

var result = {};
arr.forEach(function(item) {
  if (!result[item.category]) 
    result[item.category] = [item.question];
  else
    result[item.category].push(item.question);
});

To get to what you want from what i gave you, you can do:

var arrRequired = [];
for (var category in result){
  arrRequired.push({ 'category' : category, 'question' : result[category] });
}

If that is not what you want, then perhaps you should explain it better, using valid syntax.

Answer 2

Here is the answer to what you asked:

var object1 = JSON.parse(jsonString1);
// Do something to object1 here.
var jsonString2 = JSON.stringify(object1);