Simple Canvas example

    // get canvas and context
    var myCanvas = document.getElementById("myCanvas");
    var myContext = myCanvas.getContext("2d");

    // Draw some rectangles with different color values
    myContext.fillStyle = "red";
    myContext.fillRect(5, 5, 200, 200);
    myContext.fillStyle = "rgba(0,50,200,0.5)";
    myContext.fillRect(55, 55, 200, 200);
    myContext.fillStyle = "rgba(0,255,10,0.5)";
    myContext.fillRect(100, 100, 200, 200);
    myContext.stroke();