Pong Code

<canvas id="gc" width="640" height="480"></canvas>
<script>
p1y=p2y=40;
pt=10;
ph=100;
bx=by=50;
bd=6;
xv=yv=6;
score1=score2=0;
ais=3;
window.onload=function() {
    c=document.getElementById('gc');
    cc=c.getContext('2d');
    setInterval(update,1000/30);
    c.addEventListener('mousemove',function(e){
        p1y = e.clientY-ph/2;
    });
}
function reset() {
    bx=c.width/2;
    by=c.height/2;
     xv=-xv;
    yv=3;
}
function update() {
    bx+=xv;
    by+=yv;
    if(by<0 && yv <0) {
        yv=-yv;
    }
    if(by>c.height&&yv>0){
        yv=-yv;
    }
    if(bx<0) {
        if(by>p1y&&by<p1y+ph) {
            xv=-xv;
            dy=by-(p1y+ph/2);
            yv = dy*0.3;
        }else{
            score2++;
            reset();
        }
    }

        if(bx>c.width) {
                if(by>p2y&&by<p2y+ph) {
                        xv=-xv;
                        dy=by-(p2y+ph/2);
                        yv = dy*0.3;
                }else{
                        score1++;
                        reset();
                }
        }
   
    if(p2y+ph/2<by) {
        p2y+=ais;
    } else {
        p2y-=ais;
    }

    cc.fillStyle='black';
    cc.fillRect(0,0,c.width,c.height);
    cc.fillStyle='white';
    cc.fillRect(0,p1y,pt,ph);
    cc.fillRect(c.width-pt,p2y,pt,ph);
    cc.fillRect(bx-bd/2,by-bd/2,bd,bd);
    cc.fillText(score1,100,100);
    cc.fillText(score2,c.width-100,100);
}
</script>