Make A character go up when i press JAVASCRIPT

Hello i am making a game like flappy bird and I put up in a browser and it is not moving upwards but it is moving right like its supposed too. the main flying code is var dudeYSpeed = 0; var dudeXSpeed = 0; var dudeJumping = false; var jumpSpeed = -3;

if(mouseDown && dudeJumping === false){
    dudeJumping = true;
    dudeYSpeed = jumpSpeed;

} 

else{
    translateY += dudeYSpeed;
    dudeYSpeed += gravity;
    dudeJumping = false;
} 

translateX+=dudeXSpeed;
};