jump code

if ( this.vMotion == DO_JUMP )
{
    if ( this.canStartJump && this.onGround && this.isTouching( FlxObject.DOWN ) )
    {
        this.canStartJump = false;
        this.canJump = true;
        this.velocity.y = 0;
        this.sounds[ "jump001" ].play();
    }

    if ( this.canJump )
    {
        this.velocity.y -= this.maxVelocity.y / 16;
        if ( this.velocity.y < -( this.maxVelocity.y / 2.3 ) )
        {
            this.canJump = false;
        }
    }
}
else
{
    this.canStartJump = true;
    this.canJump = false;
}