4 ms·

I know I sound a little ignorant, but could you elaborate a little on nullability. I mean is it the same as checking whether an assignment is null or not? P.S.

• k__ 10y ago
  null and undefined are part of every type in TS, but you can tell it to exclude it from every type by default (with TS2.0). Then you are forced to check for it on every part of your code where it possibly could become null or undefined (like when data from external libs comes in etc.), so inside the TS code everything should be save to use. (no more: a && a.b && a.b.c = 123) I have the feeling that even if you would just use "any" (with excluded null and undefined) everywhere 90% of JS problems would go away.
• wpietri 10y ago
  The basic notion is that part of the meaning of a type is whether it's allowed to be null. As developers we have notions of whether some variable is supposed to ever be null; this is just asking the computer to make sure. For example, suppose you're building a simple app to remind you to call your friends on their birthdays. Your fields are name (a string), birthday (a date), and phone number (a string). Since it doesn't make sense to put somebody in without a name and birthday, you say those aren't nullable. But say you want to be able to leave a phone number out, because it's easy enough to look up their phone number when you want to call. So phone would nullable. Java, as an example, required everything variable to be typed, but all references could be null. This meant that far and away the most common error in Java logs was NullPointerException. It's great to see language features aimed at reducing that.