We help IT Professionals succeed at work.

We've partnered with Certified Experts, Carl Webster and Richard Faulkner, to bring you a podcast all about Citrix Workspace, moving to the cloud, and analytics & intelligence. Episode 2 coming soon!Listen Now

x

Creating a JSON object during run time?

rubear
rubear asked
on
Medium Priority
3,584 Views
Last Modified: 2008-03-17
I need to create a JSON object at run time.  I guess this would be an array of name/value pairs.  I am a newbie, so I'm not sure this is stated correctly.

If statically created, it would look like:

var json = [
   { x: 0, y: 110 },
   { x: 10, y: 24 },
   { x: 15, y: 63 },
   { x: 25, y: 5 },
   { x: 40, y: 98 },
   { x: 45, y: 54 },
   { x: 120, y: 1 }
 ];

So, the question is, how do I create this during run time?

Thanks,
-
Robert

Comment
Watch Question

Commented:
rubear,

You can use the very same notation. E.g. to put two vars from a form into a json formated object:

var a = docuemnt.getElementById('a').value;
var b = docuemnt.getElementById('b').value;
var c = docuemnt.getElementById('a').value;
var d = docuemnt.getElementById('b').value;

var json = [
  {"x": a, "y": b},
  {"x": c, "y": d},
];

Sam

Commented:
Also, as a side note, the JSON specification requires that member names are strings where as JavaScript is more relaxed. Your example was perfectly valid javascript but in JSON it should have been:

var json = [
   { "x": 0, "y": 110 },
   { "x": 10, "y": 24 },
   { "x": 15, "y": 63 },
   { "x": 25, "y": 5 },
   { "x": 40, "y": 98 },
   { "x": 45, "y": 54 },
   { "x": 120, "y": 1 }
 ];

See http://json.org/ for more.

Author

Commented:
Thanks for the tip about member names being strings.  What I really need to do is create the JSON object from a large data array.  The size could be perhaps 2,000 members.  So the above method won't work.  For example creating teh JSON object from XML data.

Thanks,
-
Robert
Commented:
Ah, okay. What do you want to use the data for?

JSON is just javascript objects, arrays, strings and numbers.

var myBigArray = getBigArray(); // Get a big 2d array from where ever
var myBigJson = new Array();

for(var i=0; i<myBigArray ; i++)
{
  myBigJson[i] = new Object();
  myBigJson[i]["x"] = myBigArray[i][0];
  myBigJson[i]["y"] = myBigArray[i][1];
  // Or Just
  myBigJson[i] = {"x":myBigArray[i][0], "y":myBigArray[i][1]};
}

What do you want to do with the JSON data after you create it?
If you want to use it on javascript then the above method is fine.
If you wanted to pass it back to the server or save it in a text file or something then you would need a function that would covert it to text.

-Sam

Not the solution you were looking for? Getting a personalized solution is easy.

Ask the Experts

Author

Commented:
I am trying to plot via an dojo SVG library which is wanting an object in this format.  I finally tried this, which works:

json = [];
for(i=0; i !=360; i++)
{
    json.push( {"x":i, "y": Math.sin(i*Math.PI/180)} );
}

I'll try your method above as well.

Thanks,
-
Robert

Author

Commented:
OK, thanks,
Both methods work.  

The more proper syntax for my mthod is probably:

 var json = new Array();

for(var i=0; i !=360; i++)
{
     json.push( {"x":i, "y": 100+ 50*Math.sin(i*Math.PI/180)} );
}

I'll accept your awnser, thanks!
Access more of Experts Exchange with a free account
Thanks for using Experts Exchange.

Create a free account to continue.

Limited access with a free account allows you to:

  • View three pieces of content (articles, solutions, posts, and videos)
  • Ask the experts questions (counted toward content limit)
  • Customize your dashboard and profile

*This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.

OR

Please enter a first name

Please enter a last name

8+ characters (letters, numbers, and a symbol)

By clicking, you agree to the Terms of Use and Privacy Policy.