this post was submitted on 06 Jul 2023
550 points (97.6% liked)
Programmer Humor
19197 readers
1362 users here now
Welcome to Programmer Humor!
This is a place where you can post jokes, memes, humor, etc. related to programming!
For sharing awful code theres also Programming Horror.
Rules
- Keep content in english
- No advertisements
- Posts must be related to programming or programmer topics
founded 1 year ago
MODERATORS
you are viewing a single comment's thread
view the rest of the comments
view the rest of the comments
not sure the distinction between null and undefined is doing anything for me here
Basically JavaScript uses undefined to mean keys that don't exist. You know how sometimes when you're wondering about the semantics of "present but null" and "absent"? It's basically that. Undefined means it isn't there but things are only null if they've been set to null.
There are probably more nuances but that is the gist.
One is missing but has expected values, the other is completely unknown, like an unimplemented function.
Depends on the programming language. In JavaScript, it literally means that like the key or variable does not actually exist. Whereas like in C/C++, writing random bytes to random memory addresses would result in "undefined behaviour" which means basically anything could happen.
In Javascript you can do
let a = undefined, defining the varialeaasundefined.A significant difference to defining it as
nullis thattypeof null == "object", whiletypeof undefined == "undefined".