Why null?

[sindresorhus]

I personally think it should be undefined, but either choice should be defended in the proposal.

[arthurfiorette]

All of your points makes a lot of sense. Will change to the next proposal rewrite as well defend the usage of undefined.

I guess

• typeof null === 'object'
• default parameters only work with undefined

are both very strong arguments in favor of undefined.

[felippe-regazio]

Maybe could be helpfull to say that null has a "synthetic use". The JS compiler/interpreter/engine will always assign undefined to indicate the absense of a value.

[bmeck]

This actually is a difference in JS vs WHATWG specs commonly brought up. JS specifications should return undefined while DOM generally prefers null.

[felippe-regazio]

This actually is a difference in JS vs WHATWG specs commonly brought up. JS specifications should return undefined while DOM generally prefers null.

I see. But we cannot merge SPECs. The DOM is not part of the JavaScript SPEC, but is instead a Web API with follows another SPEC (https://www.w3.org/TR/1998/WD-DOM-19980416/). Since this proposal is being opened to JS I'm proposing to follow the specification guidelines. Per SPEC JS defines null as "primitive value that represents the intentional absence of any object value" (https://tc39.es/ecma262/#sec-null-value). Since we are talking about "safe check" for unintentional behavior, my point its that "undefined" may fit better.

[ishank-s]

++ we should just nuke null from javascript.
It doesn't get caught in default variables in params.It's typeof null === 'object'. It's such a footgun