something like this?

not tested...

1. void draw () {
2. background(0);
3. println("===========================================================");
4. int numberOfElements = obj.length();
5. //
   
6. // for loop
7. for (int j = 0; j < numberOfElements; j++) {
8.   //
9.   JSONObject entry = obj.getJSONObject(j);
10.   println ("Now we show entry # " + j );
11.   println (entry);
12.   int x = (entry.getString("x"));
13.   int y = (entry.getString("y"));
14.   println (x + ", " + y);
15.  
16.   fill(20, 255, 160);

17.  ellipse(x, y, 20, 20);

18.   println ("----------------------");
19.   //
20. } // for
21. } // draw

Hi Chrisir, unfortunately that does not seem to work. I don't think I'm able to put pure javascript directly into the pde file without using something else. From what I've read it seems like I need to call processing functions including draw from my javascript?

The processing code locks up as soon as it hits 'int numberOfElements = obj.length();'

The same thing happens if I declare a variable in javascript in the <script> tag. I cannot access it directly from the processing pde file.

This fails:

1. void setup(){ 
   

2.       size(200, 200); 
   

3. } 
   

4. void draw(){ 
   

5.       background(0);
         fill(20, 255, 160);
         ellipse(100, 100, 20, 20);     
   

6.       println(test); //var test = 999; is global js variable
   

7. }

Thanks for trying. Any other help would be much appreciated.

sorry, I was thinking processing, not processing.js  

here is an example -- processing, not processing.js  

http://forum.processing.org/topic/simple-json-example-with-api

Does anyone know how to parse JSON data with Processing.js? None of the standard Processing libraries are applicable because they only run in the Java version. I'm building web tools so I'm stuck with a crude hack in which I count start and end characters and then use substring() to parse my data.... There has to be a more graceful way to do this!

Here you go: 

Thanks florentd for the response. I did look at Pomax's guide but had trouble understanding that. I was able to figure out my own way of getting the JSON data though. For anyone interested, here's what I ended up doing:

AJAX results bit:

1. var pjs = Processing.getInstanceByID('your_canvas_id');

2. var obj = JSON.parse(xmlHttp.responseText);

3. var obj_array = new Array();

4. var v = 0;

5. do{

6.       obj_ar[v] = [obj[v].x, obj[v].y];

7.       v++;

8. }while(v < obj.length);

9. pjs.my_processingjs_func(obj_ar);
   

   
   

processing.js PDE file:

1. void my_processingjs_func(my_obj_ar){

2.       alert(my_obj_ar[0][0]);

3.             //assign values etc...
   
4. }