Declare a JSON array of Objects and add items dynamically

Question

This is stupid but i am missing something and could not reach the conclusion. I am trying to initialize a JSON Array and trying to add JSON Objects to it run time. For an example, I will be getting the list of repeated values from server something like below.

"employees":[
    {"firstName":"John", "lastName":"Doe"},
    {"firstName":"Anna", "lastName":"Smith"},
    {"firstName":"Peter", "lastName":"Jones"}
]

I have to create an array of object and fill these values in it.

I am trying to initialize an array like

var myArr = [];

and I want to add object with properties to it dynamically, something like below.

var myobj = {}

for(int i=0;i<length;i++)
{
myobj[i].name = serverrespOBJ.name;
myobj[i].lastName= 'serverrespOBJ.lastname';
myArr.push(myobj)
}

I am getting the error that name can not be added to undefined, so i believe, my way of adding items to the object is incorrect.

I am trying to find a good example but could not get it. Any help would be appreciated.

Thanks

You should pick a correct answer!

Waqar Alamgir
– Waqar Alamgir

2014-07-01 06:36:51 +00:00
Commented Jul 1, 2014 at 6:36 — Waqar Alamgir
– Waqar Alamgir, Commented Jul 1, 2014 at 6:36

Alnitak · Accepted Answer · 2014-06-30 16:30:58Z

5

You'll be wanting something like this:

var data = { employees: [] }   // initially empty

data.employees.push( {
    firstName: 'John',
    lastName: 'Doe'
} );

answered Jun 30, 2014 at 16:30

Alnitak

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4 Comments

Alnitak Over a year ago

@Gendaful no, please don't do that, it invalidates answers already provided.

Alnitak Over a year ago

@Gendaful in any event, your problem is that you need to create myobj inside the loop, otherwise you're just adding the same object to the array over and over. You also need to lose the [i] dereference - myobj is an object, not an array.

Gendaful Over a year ago

Thanks Alnitak, So in short, I am creating an array myArr and then creating myObj inside for loop such as myObj = {}. After that, I am adding the items such as myobj.name = 'abc, myobj.lastname = def etc. and then adding the obj to the array like myarr.push(myobj), but whenever I am trying to retrieve it with myarray[0].name, it always returns undefined, what do you think I am missing here?

Alnitak Over a year ago

@Gendaful perhaps the source data you're trying to put into myObj is undefined?

Sabri Aziri · Accepted Answer · 2014-06-30 16:33:12Z

1

Its simple init first the object or array you want to play dynamicly e.x:

var myArr = [], myObj = {};

Now if adding element to them:

myArr.push(10);
myObj.new = 10 or myObj['new'] = 10

More advanced :

myArr.push(myObj); //[10, {'new':10}] --> looks our object

answered Jun 30, 2014 at 16:33

Sabri Aziri

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Comments

Waqar Alamgir · Accepted Answer · 2014-06-30 16:36:13Z

1

You can init a new json object like this:

var jsonObj = {};
jsonObj.employees = [];
jsonObj.employees.push({"firstName":"Waqar", "lastName":"Alamgir"});

or add data in existance like this:

var jsonObj = {
    "employees":[
        {"firstName":"John", "lastName":"Doe"},
        {"firstName":"Anna", "lastName":"Smith"},
        {"firstName":"Peter", "lastName":"Jones"}
    ]
};

jsonObj.employees.push({"firstName":"Waqar", "lastName":"Alamgir"});

console.log(jsonObj);

edited Jun 30, 2014 at 16:36

answered Jun 30, 2014 at 16:30

Waqar Alamgir

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4 Comments

Waqar Alamgir Over a year ago

This is a valid JSON!

Alnitak Over a year ago

No, it isn't. JSON is a string serialisation format. What you have is a JS object literal.

Waqar Alamgir Over a year ago

The one you are talking about is array JSON encoded, user is asking about JSON array!!

Alnitak Over a year ago

No, there's no such thing as a "JSON array". There are "arrays encoded in JSON format". No such entity appears in the question, nor in your answer.

Robin Rizvi · Accepted Answer · 2014-06-30 16:39:20Z

1

Check this fiddle - http://jsfiddle.net/FamBn/1/

HTML:

<input type="text" id="firstname" />
<input type="text" id="lastname" />
<input type="submit" id="add" />
<div id="dsp"></div>

JS:

var employees=[
{"firstName":"John", "lastName":"Doe"},
{"firstName":"Anna", "lastName":"Smith"},
{"firstName":"Peter", "lastName":"Jones"}
];

$('#add').click(function(){
    var fname=$('#firstname').val();
    var lname=$('#lastname').val();
    employees.push({
        firstName: fname,
        lastName: lname
    });
    var output = '';
    for (var i=0; i<employees.length; i++) {
        output += "FirstName: " + employees[i].firstName + " LastName: " + employees[i].lastName;
    }
    $('#dsp').html(output);
    console.log(employees);
});

edited Jun 30, 2014 at 16:39

answered Jun 30, 2014 at 16:33

Robin Rizvi

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