Im new to javaScript game development and I need to move a rectangle i created down for a simple movement in the game im making

player.downMovement = function() {
            let downBtn = document.getElementById('moveDown')
            downBtn.addEventListener('click', function movePlayerDown(){
                let playerY = player.y - 20
                function clearPlayer() {
                    ctx.clearRect(100, playerY + 20, 20, 20)
                }
                player.y = player.y + player.height;
                setTimeout(clearPlayer, 10)
            
            })  
            player.draw();
        }