Want to to know when exactly an online static web-page was last time updated?

Just put the below code in the browser's address field:
javascript:alert(document.lastModified)
_{NOTE: Most browsers tends to cut down the javascript: part when you paste it, so most likely you have to type it by hand.}

^{WE ARE ON A BLOCKCHAIN SO... [disclaimer] This is a new re-edited post on an old deleted one (so saved to the same blockchain block/link) and this is why you may notice discrepancies in such things as the first hashtag, title/permalink to the blockchain, date of the post, topic/date of the comments, reported likes and their date and so on.}