Încercați-vă singur - JavaScript Reference canvas_globalcompop

<!DOCTYPE html>
<html>
<head>
<style>
canvas {
   border: 1px solid #d3d3d3;
   margin-right: 10px;
   margin-bottom: 20px;
}
</style>
</head>
<body>

<script>

var gco = new Array();
gco.push("source-atop");
gco.push("source-in");
gco.push("source-out");
gco.push("source-over");
gco.push("destination-atop");
gco.push("destination-in");
gco.push("destination-out");
gco.push("destination-over");
gco.push("lighter");
gco.push("copy");
gco.push("xor");

var n;
for (n = 0; n < gco.length; n++) {
        document.write("<div id='p_" + n + "' style='float:left;'>" + gco[n] + ":<br>");
        var c = document.createElement("canvas");
        c.width = 120;
        c.height = 100;
        document.getElementById("p_" + n).appendChild(c);
        var ctx = c.getContext("2d");
        ctx.fillStyle = "blue";
        ctx.fillRect(10, 10, 50, 50);
        ctx.globalCompositeOperation = gco[n];
        ctx.beginPath();
        ctx.fillStyle = "red";
        ctx.arc(50, 50, 30, 0, 2 * Math.PI);
        ctx.fill();
        document.write("</div>");
        }

</script>

</body>
</html>