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!

• RaYell: It's generally better to initialize array like this var msg = []; instead of var msg = new Array();

Answer 1

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.

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

Answer 2

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);
}

Answer 3

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); 
}