JS dynamic page loading problem

  node.js, question

I am a junior. What I am doing now is that after the student logs in, he can see the recent activities (starting time, place and number of participants) of inside in the school. He can choose to participate. When the activity is full, he cannot participate. That is as simple as that.
The question is: My back end is PHP and the front end is js dynamic. I don’t know which data format is more convenient to use to return js from the database (simple and easy to learn, pursuing efficiency without considering performance), and then I use what method to insert elements into the page inside (is DOM convenient or easy to typeset)?图片描述

This is the front page I just made.

Json is the most convenient.