Multi-Pass Color Sort Lamba X and Lambda Y

col.js.html

<canvas id="canvas" width="256" height="256"></canvas>
<script type="text/javascript">
 	var canvas = document.getElementById("canvas");
    var ctx = canvas.getContext("2d");
    var imgdata = ctx.createImageData(canvas.width, canvas.height);
    function set_pixel (x, y, r, g, b) { var index = (x + y * imgdata.width) * 4; imgdata.data[index + 0] = r; imgdata.data[index + 1] = g; imgdata.data[index + 2] = b; imgdata.data[index + 3] = 255; };
	function swap_pixels (x1, y1, x2, y2) { var p1 = get_pixel(x1, y1); var p2 = get_pixel(x2, y2); set_pixel(x1, y1, p2[0], p2[1], p2[2]); set_pixel(x2, y2, p1[0], p1[1], p1[2]);	};
	function get_pixel (x, y) { var index = (x + y * imgdata.width) * 4; return [imgdata.data[index + 0], imgdata.data[index + 1], imgdata.data[index + 2]]; };
	function draw () { ctx.putImageData(imgdata, 0, 0);	};
	function prep () {
		// meant for 4096x4096 canvas, slow as fuck
		var r = 0;
		var g = 0;
		var b = 0;
		for (var x = 0; x < canvas.width; x++) {
			for (var y = 0; y < canvas.height; y++) {
				set_pixel(x, y, r, g, b);
				b++;
				if (b > 255) {
					b = 0;
					g++;
					if (g > 255) {
						g = 0;
						r++;
					}
				}
			}
		}
		draw();
	};
	function preprandom () {
		// way prettier
		for (var x = 0; x < canvas.width; x++) for (var y = 0; y < canvas.height; y++) set_pixel(x, y, Math.floor(Math.random() * 255), Math.floor(Math.random() * 255), Math.floor(Math.random() * 255));
		draw();
	};
	function multi_pass_sort (lambda_x, lambda_y) {
		var sorted = true;
		for (var x = 1; x < canvas.width; x++) for (var y = 0; y < canvas.height; y++) if (lambda_x(get_pixel(x - 1, y), get_pixel(x, y))) { swap_pixels(x - 1, y, x, y); sorted = false; }
		for (var x = 0; x < canvas.width; x++) for (var y = 1; y < canvas.height; y++) if (lambda_y(get_pixel(x, y - 1), get_pixel(x, y))) { swap_pixels(x, y - 1, x, y); sorted = false; }
		draw();
		if (!sorted) setTimeout(function () { multi_pass_sort(lambda_x, lambda_y); }, 0);
		else console.log('done!');
	};
	//prep();
	preprandom();
	setTimeout(function () { multi_pass_sort(function lambda_x (a, b) { return a[0] > b[0] || a[1] > b[1]; }, function lambda_y (a, b) { return a[1] > b[1] || a[2] > b[2]; });
	}, 1000);
</script>