问如何检测我的智能设备是否可触摸？

EN

var canvas,
    c,
    container,
    // is this running in a touch capable environment?
    touchable = 'createTouch' in document,
    touches = []; // array of touch vectors
var firstboot = true;
lastFrameTimeStamp = new Date().getTime();

function init() {
    if (touchable) {
        setupCanvas();
        setInterval(draw, 1000 / 24);
        canvas.addEventListener('touchstart', onTouchStart, false);
        canvas.addEventListener('touchmove', onTouchMove, false);
        canvas.addEventListener('touchend', onTouchEnd, false);
        window.onorientationchange = resizeCanvas;
        window.onresize = resizeCanvas;
    }
    else {
        setupCanvas();
        c.textAlign="center";
        c.fillStyle = '#000';
        c.font="18px Arial";
        c.fillText("Helaas, de controller is alleen beschikbaar voor toestellen met een touchscreen.",canvas.width/2,canvas.height/2);   
    }
}