The Tor Browser / file revision

 // Adapted from

 //

 // https://github.com/RiverTrail/RiverTrail/blob/master/examples/mandelbrot/mandelbrot.js

 //

 // which in turn is adapted from a WebCL implementation available at

 //

 // http://www.ibiblio.org/e-notes/webcl/mandelbrot.html

 load(libdir + "parallelarray-helpers.js");

 var nc = 30, maxCol = nc*3;

 // this is the actual mandelbrot computation, ported to JavaScript

 // from the WebCL / OpenCL example at

 // http://www.ibiblio.org/e-notes/webcl/mandelbrot.html

 function computeSetByRow(x, y) {

   var Cr = (x - 256) / scale + 0.407476;

   var Ci = (y - 256) / scale + 0.234204;

   var I = 0, R = 0, I2 = 0, R2 = 0;

   var n = 0;

   while ((R2+I2 < 2.0) && (n < 512)) {

     I = (R+R)*I+Ci;

     R = R2-I2+Cr;

     R2 = R*R;

     I2 = I*I;

     n++;

   }

   return n;

 }

 function computeSequentially() {

   result = [];

   for (var r = 0; r < rows; r++) {

     for (var c = 0; c < cols; c++) {

       result.push(computeSetByRow(r, c));

     }

   }

   return result;

 }

 var scale = 10000*300;

 var rows = 4;

 var cols = 4;

 // check that we get correct result

 if (getBuildConfiguration().parallelJS) {

   var expected = computeSequentially();

   assertParallelExecSucceeds(

     function (m) Array.buildPar(rows * cols, function (xy) {

       return computeSetByRow((xy/cols)|0,(xy%cols))

     }, m),

     function (r) assertStructuralEq(expected, r));

 }