работать из-за безопасности конечно не будет (почти), но как вариант
<!doctype html>
<html>
<meta charset='utf-8'>
<head>
<title></title>
</head>
<body>
<script>
function fn(url, callback) {
var canvas = document.createElement('canvas'),
context = canvas.getContext('2d'),
pic = new Image();
pic.crossOrigin = "Anonymous";
pic.onload = function() {
canvas.width = pic.width;
canvas.height = pic.height;
context.drawImage(pic, 0, 0);
var imageData = context.getImageData(0, 0, pic.width, pic.height);
var pix = imageData.data;
var transparent = false;
for (var i = 0, n = pix.length; i < n; i += 4) {
if (pix[i + 3] == 0) {
transparent = true;
break
}
}
callback(transparent)
};
pic.src = url
}
var url = 'http://5.firepic.org/5/images/2015-11/23/zmda01sjsdpe.png',
callback = function(a) {
alert(a)
};
fn(url, callback)
</script>
</body>
</html>