12. undefined is special #

Created Tuesday 1 March 2022

• [ ] in vault

• When variables are “hoisted”, they are set to undefined.

• This is therefore a value set by the JavaScript engine.

Good practice #

So, we should never assign a variable to undefined ourselves. This is because it makes it difficult to debug, because undefined is supposed to be provided by the JS engine.

Instead, use the keyword null if a value needs to be explicitly shown that it does not exist.