How to add values to a JSON object?

Question

I have created an array with:

var msg = new Array();

then, I have a function that add values to this array, this function is:

function add(time, user, text){
    var message = [time, user, text];
    if (msg.length >= 50)
        msg.shift();

    msg.push(message);        
}

As you can see, if the array has 50 or more elements I remove the first with .shift(). Then I add an array as element.

Ok, the code works perfectly, but now I have to loop the msg array to create a JSON obj.

The JSON object should has this format:

var obj = [
{'time' : time, 'user' : user, 'text' : text},
{'time' : time, 'user' : user, 'text' : text},
{'time' : time, 'user' : user, 'text' : text}
]

I mean...i have to loop msg array and then store all the values inside the JSON object. I do not know how to "concatenate" the element of the array inside json obj.

Could you help me?

Thank you very much in advance!

It's generally better to initialize array like this var msg = []; instead of var msg = new Array(); — RaYell
– RaYell, Commented Jun 11, 2010 at 8:21

Luca Matteis · Accepted Answer · 2010-06-11 08:19:35Z

10

I'll give you an example from your add function:

function add(time, user, text){
    // this line is all I changed
    var message = {'time' : time, 'user' : user, 'text' : text};

    if (msg.length >= 50)
        msg.shift();

    msg.push(message);        
}

As you can see the message variable is no longer an array but it's the Object you want it to be.

From this you should be able to work out how to create a new array and add the values you want to it.

answered Jun 11, 2010 at 8:19

Luca Matteis

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1 Comment

Damiano Over a year ago

ok but, after it msg is an array, not a JSON object...how to convert?

RaYell · Accepted Answer · 2010-06-11 08:20:38Z

1

Try this:

var len = msg.length;
var obj = [];
for (var i = 0; i < len; i++) {
    var item = {
        'time': msg[i][0],
        'user': msg[i][1],
        'text': msg[i][2]
    }
    obj.push(item);
}

answered Jun 11, 2010 at 8:20

RaYell

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Comments

slebetman · Accepted Answer · 2010-06-11 08:22:04Z

0

I think you want something like this:

function add(time, user, text){
  var message = {time:time, user:user, text:text};
  if (msg.length >= 50)
    msg.shift();

  msg.push(message);        
}

answered Jun 11, 2010 at 8:22

slebetman

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