This a unlimited-colors project in which there are unlimited colors changing and you can stop on one of them.
1.) generate random color by Math.random() function.
2.) select start and stop button from DOM tree.
3.) on start button add event listener so that by clicking over it background color start changing.
4.) for start changing color function we use setInterval which change background color every second by picking random color value.
5.) to stop changing color we use clearInterval and set flush out all previous values too.