This is an accurate stopwatch script that uses setInterval(getShowtime(), 1).
getShowtime() will thus run every millisecond. It checks the current time and compares it to the amount of time elapsed, then displays the difference to the user. It does not rely on setInterval to determine the amount of time passed because that is a highly inaccurate way to keep track of time in javascript.
Also included is a pause button, reset button, and some basic styling.
You can easily change the script to run every second by running setInterval(getShowTime(), 1000) instead of setInterval(getShowTime(), 1). If you choose to run it every second, you should probably comment out the millisecond display options in the getShowTime() function.
Example usage below. Go to the page and click the Timer link. On this website we are using it to run every second, but the script in this repository will run in milliseconds. You can also include the days, just comment the days code in the getShowTime() function.
https://brainbank.cc/jamie/words/words-in-the-news-december-2018
Will display as :
00:00:00:000 or hours:minutes:seconds:milliseconds
Included in the HTML is a link to the Google Font being used as well as Font Awesome, which is used to display the Play and Pause buttons.