jquery True event, when the page scrolls to the top of each p, execute an event
You $("p") can get all p. Then postion().top will have their top, and then in your scroll event, judge that the current scroll height exceeds that, and trigger something
You $("p") can get all p. Then postion().top will have their top, and then in your scroll event, judge that the current scroll height exceeds that, and trigger something