Change getItem's default to undefined

[avi12]

Is your feature request related to a bug?

N/A

Feature request

Suppose I want to fetch multiple storage values, currently, it'll look like:

const [value1, value2] = await Promise.all([
  storage.getItem<Type1>("local:key1").then(val => val ?? "foo"),
  storage.getItem<Type2>("local:key2").then(val => val ?? "bar")
]);;

I prefer having this code instead:

const [value1 = "foo", value2 = "bar"] = await Promise.all([
  storage.getItem<Type1>("local:key1"),
  storage.getItem<Type2>("local:key2"),
]);

which can be achieved without triggering a TypeScript error by changing null to undefined in

wxt/packages/wxt/src/storage.ts

Line 309 in e3f00d2

const getFallback = () => opts?.fallback ?? opts?.defaultValue ?? null;

[aklinker1]

The storage API has a built-in way of providing default values.

const [value1, value2] = await Promise.all([
  storage.getItem<Type1>("local:key1", { fallback: "foo" }),
  storage.getItem<Type2>("local:key2", { fallback: "bar" }),
]);

The storage APIs were designed to feel similar to localStorage, which is why it currently returns null instead of undefined. At this point, it would be a pretty disruptive breaking change to make.

I'm not necessarily opposed to this, undefined does make sense in many ways, but this would be really annoying to migrate to. So many little edge cases and checks (like someone accidentally used === null insetad of == null, etc).

[avi12]

Huh, I was not aware of the { fallback: ... } second argument

[avi12]

But does it actually affect getItem's return type to get rid of null?

[baraich]

@avi12, I have fixed the type issue and made the pull request (9516324) and once merged the issue would resolved in production.