var elmButton = document.querySelector('.click_handler') var elmHeading1 = document.querySelector('.click_heading') var over_out_element = document.querySelector('.over_out_handler'); var enter_leave_element = document.querySelector('.enter_leave_handler'); var key_up_down_element = document.querySelector('.key_up_down_handler'); var key_up_down_heading = document.querySelector('.key_up_down_text') elmButton.addEventListener('click', function () { elmHeading1.textContent = 'THE BUTTON IS CLICKED' }) elmButton.addEventListener('dblclick', function () { elmHeading1.textContent = 'THE BUTTON IS DOUBLE CLICKED' }) over_out_element.addEventListener('mouseover', function () { over_out_element.style.backgroundColor = '#ff4747' }) over_out_element.addEventListener('mouseout', function () { over_out_element.style.backgroundColor = '#ffa500' }) enter_leave_element.addEventListener('mouseenter', function () { enter_leave_element.style.border = '5px solid #ff0000' }) enter_leave_element.addEventListener('mouseleave', function () { enter_leave_element.style.border = '0px solid #ff0000' }) key_up_down_element.addEventListener('mousedown', (event) => { if (0 === event.button) {// Left Button Pressed key_up_down_heading.textContent = "Left Mouse Key Pressed"; } else if( 1 === event.button ) { // Middle Button Pressed key_up_down_heading.textContent = "Middle Mouse Key Pressed"; } else if( 2 === event.button ) { // Right Key Pressed key_up_down_heading.textContent = 'Right Mouse Key Pressed'; } })