SOURCE

       var canvas = document.getElementById("canvas");
        canvas.width = 800;
        canvas.height = 600;
        var context = canvas.getContext("2d");

        context.lineWidth = 50;
        context.strokeStyle = "#1BAAAA";

        context.beginPath();
        context.moveTo(100,100);
        context.lineTo(700,100);
        context.lineCap = "butt";
        context.stroke();

        context.beginPath();
        context.moveTo(100,300);
        context.lineTo(700,300);
        context.lineCap = "round";
        context.stroke();

        context.beginPath();
        context.moveTo(100,500);
        context.lineTo(700,500);
        context.lineCap = "square";
        context.stroke();

<canvas id="canvas">
</canvas>