ES6 has been out for a while now, but your JavaScript courses are still using concepts like the var keyword, which is now obsolete.  I have two issues with this.  First of all, when I try to use const or let, the green monster gets upset with me, which it shouldn't.  Const and let are now JavaScript best practices.  Secondly, if you're going to teach people to program, you need to teach them that programming languages change and adapt.  What might have been the standard for years might one day become obsolete, as what happened with var.  These courses should be updated with current standards.