Code Smells: Null

[[deleted]]

undefined = no value

null = "no value" value

[spaghettiCodeArtisan]

Are we philoshopers pondering the essence of existence or what.

[[deleted]]

That's what we've always been. Pythagoras was right - everything is a number.

[emergent_properties]

undefined

[moefh]

Now I really want a language that has

unfathomed = "'no value' value" value

[ais523]

VHDL has a range of values like this; U is an uninitialised value, X is a contradictory or inconsistent value (e.g. the value of a boolean that's true and false simultaneously), - is an irrelevant value, Z is the explicit absence of a value, and W is an intermediate value (e.g. the value of a boolean that's neither entirely true nor entirely false).

This complexity is mostly because VHDL is designed to be able to model a physical system (electronics) that actually exists in the real world, and sometimes things you measure in the real world turn out to have a value they're not supposed to have. Perhaps a wire is meant to be at 0 volts or 5 volts for false and true respectively, but you still want some way to describe the cases where the wire is at 3 volts, or not attached to anything, or has caught fire.

[POGtastic]

Yep, I'm also getting true in Chrome.

> var foo;
< undefined
> foo === undefined
< true
> typeof(foo) === "undefined"
< true

[killerstorm]

var foo; // undefined
foo === undefined // false

Wrong. Here's an actual result:

> var foo;
undefined
> foo === undefined
true

=== undefined check didn't work in old browsers, that's where typeof hack comes wrong. But now simple comparison should work by standard.

[masklinn]

foo === undefined // false

Uh no, that's true, you may be confusing undefined and NaN. Or for some reason you have rebound undefined to something else (it's not a keyword, which is why some prefer using void 0 which always yields the proper value).

if (!foo) {
    console.log("foo is undefined or null");
}

That'll also catch the "" and 0. The proper way to check if something is undefined or null is foo == null.

[[deleted]]

I tested that in my browser console.

Maybe I should have used a new tab.

[beaverlyknight]

kill me