The exact code cannot be executed in HTML .Moreover as explained in the lectures we use JS to perform task more efficiently without using the bandwidth. JS is a better option as tasks are completed at web page itself.
And google charts library supports java script format.
So if you want to perform the task in html you have to code it yourself which will use bandwidth and it will be difficult.
‘time_stamp’ is a parameter which represents a point in time independent of any time zone ,represented as seconds or nanoseconds resolution. It marks the time that an event occurred.
In this case it marks the time for which light intensity is recorded.
No not the average value but the exact value at every 5th minute is sent(if for 5 minutes is set)