title: What happens if I used Javascript deprecated features?
body: <p>I am writing a program that intercepts user’s keystrokes to decide whether to display or reject the characters. The keypress event is more convenient for this analysis than keyup and keydown because I analyze only letters and digits, all other characters and their combinations are allowed to go through. Meanwhile, <a href="https://www.freecodecamp.org/news/javascript-keycode-list-keypress-event-key-codes/" rel="nofollow noreferrer">https://www.freecodecamp.org/news/javascript-keycode-list-keypress-event-key-codes/</a> recommends keydown and keyup against keypress. It says “Moreover, the keypress event has been deprecated. This is a big enough reason to avoid it.” How important is it to avoid deprecated features? What happens if I use them? Thank you for your help.</p>