var canvas = document.getElementById('canvas');
  var canvasWidth = canvas.width;
  var canvasHeight = canvas.height;
  var ctx = canvas.getContext('2d');
  var imageData = ctx.getImageData(0, 0, canvasWidth, canvasHeight);
  
  var data = imageData.data;
  
  
  var buf = new ArrayBuffer(imageData.data.length);
  var buf8 = new Uint8ClampedArray(buf);
  var data32 = new Uint32Array(buf);
  
  var pixels = new Int32Array(imageData.data.buffer);

Teardown JS



            ctx.putImageData(imageData, 0, 0);

Test cases

Test #1

Title *

Async

Code *

var c = 0;
var len = data.length / 4;

for (var i = 0; i < len; i++) {

  var alpha = data[i + 3];
  if (alpha !== 0) {
    c++;
  }
}

Test #2

Title *

Async

Code *

var c = 0;

var c = 0;
var len = pixels.length;

for (var i = 0; i < len; i++) {

  var alpha = (pixels[i] >> 24) & 0xFF;
  if (alpha !== 0) {
    c++;
  }
}

Test #3

Title *

Async

Code *

var c = 0;
var len = pixels.length;

for (var i = 0; i < len; i++) {
  var alpha = pixels[i] & 0xFF000000;
  if (alpha !== 0) {
    c++;
  }
}

Test case details

Preparation Code

Test cases

Test #1

Test #2

Test #3