People help please-how to make the function so that when you click on a red square, a random color would appear

Question

https://code.sololearn.com/WYVv8jYuF2iu/?ref=app

Answer 1

Colors are 3 bytes

var num = Math.floor(Math.random() * (0xffffff + 1));
var hexColor = "#" + num.toString(16)

Answer 2

no works