2 個矩形是否發生碰撞

// rectangle objects { x:, y:, width:, height: }
// return true if the 2 rectangles are colliding
// r1 and r2 are rectangles as defined above

function RectsColliding(r1,r2){
    return !(
        r1.x>r2.x+r2.width || 
        r1.x+r1.width<r2.x || 
        r1.y>r2.y+r2.height || 
        r1.y+r1.height<r2.y
    );
}