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DMD3475/week-9/stopwatch.html
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| <!DOCTYPE html> | |
| <html lang="en-US"> | |
| <head> | |
| <meta charset="utf-8"> | |
| <title>setInterval stopwatch</title> | |
| <style> | |
| p { | |
| font-family: sans-serif; | |
| } | |
| </style> | |
| </head> | |
| <body> | |
| <p class="clock"></p> | |
| <p><button class="start">Start</button><button class="stop">Stop</button><button class="reset">Reset</button></p> | |
| <script> | |
| // Define a counter variable for the number of seconds and set it to zero. | |
| let secondCount = 0; | |
| // Define a global to store the interval when it is active. | |
| let stopWatch; | |
| // Store a reference to the display paragraph in a variable | |
| const displayPara = document.querySelector('.clock'); | |
| // Function to calculate the current hours, minutes, and seconds, and display the count | |
| function displayCount() { | |
| // Calculate current hours, minutes, and seconds | |
| let hours = Math.floor(secondCount/3600); | |
| let minutes = Math.floor((secondCount % 3600)/60); | |
| let seconds = Math.floor(secondCount % 60) | |
| // Display a leading zero if the values are less than ten | |
| let displayHours = (hours < 10) ? '0' + hours : hours; | |
| let displayMinutes = (minutes < 10) ? '0' + minutes : minutes; | |
| let displaySeconds = (seconds < 10) ? '0' + seconds : seconds; | |
| // Write the current stopwatch display time into the display paragraph | |
| displayPara.textContent = displayHours + ':' + displayMinutes + ':' + displaySeconds; | |
| // Increment the second counter by one | |
| secondCount++; | |
| } | |
| // Store references to the buttons in constants | |
| const startBtn = document.querySelector('.start'); | |
| const stopBtn = document.querySelector('.stop'); | |
| const resetBtn = document.querySelector('.reset'); | |
| // When the start button is pressed, start running displayCount() once per second using setInterval() | |
| startBtn.addEventListener('click', () => { | |
| stopWatch = setInterval(displayCount, 1000); | |
| startBtn.disabled = true; | |
| }); | |
| // When the stop button is pressed, clear the interval to stop the count. | |
| stopBtn.addEventListener('click', () => { | |
| clearInterval(stopWatch); | |
| startBtn.disabled = false; | |
| }); | |
| // When the reset button is pressed, set the counter back to zero, then immediately update the display | |
| resetBtn.addEventListener('click', () => { | |
| clearInterval(stopWatch); | |
| startBtn.disabled = false; | |
| secondCount = 0; | |
| displayCount(); | |
| }); | |
| // Run displayCount() once as soon as the page loads so the clock is displayed | |
| displayCount(); | |
| </script> | |
| </body> | |
| </html> |