Local storage is an untyped interface external to the frontend code
itself. The `data` field after `JSON.parse`'d from `raw_data` can be
further validated using `zod`'s schema `formDataSchema`.
The test case `server_upgrade_alert hide_duration_expired` in
`navbar_alerts.test.js` has a bug at `start_time`, which is fixed in
this commit. `start_time` is a mock value of `Date.now()` used in
`localstorage.ts`, which will concatenate with a number `expires`.
So `start_time` was supposed to be an integer value. Before fix, `new
Date(1620327447050)` returns a `Date` object which is wrongly
concatenated with `expires`.
Fixes#24997.
Added function parameter types, return type, and types of local
varaibles. Added a `null` check for `raw_data` before `JSON.parse`.
Created a type `FormData` and an export type `LocalStorage` to
imporve conciseness and clearity.
Type `LocalStorage` is exported because it might be used in other
files based on an observation that many files have imported `localstorage`.
Tim Abbott
AcKindle3