treefit

2 years ago

treefit
2 years ago

Use typescript, they said. Your types will be safe, they said. 😭

type T = { h: number }
// As expected we get an error here
function justReturn(s: T): T {
return { h: 7, hello: '' }
}
// Why are those working?
function returnVar(s: T): T {
let t = { h: 7, hello: '' }
return t
}
function returnConst(s: T): T {
const t = { h: 7, hello: '' }
return t
}

the error:
Type '{ h: number; hello: string; }' is not assignable to type 'T'.
Object literal may only specify known properties, and 'hello' does not exist in type 'T'.

type T = {a:number}
function setState(cb: (prevState: T) => T) {}
// All good
setState((_prevState) => ({a: 12}))
// Proper error, also good
setState((_prevState) => ({b: 12}))
// oehm, typescript? No error? Maybe because of ...spread syntax?
setState((prevState) => ({...prevState, b: 12}))
// Event without spread syntax no type error??
setState((prevState) => ({a: prevState.a, b: 13}))
// But here tsc complains or what?
const test: T = {a: 12, b: 13}

in reply to treefit

Jikstra

in reply to treefit 2 years ago

This just caused us one week of headaches on #deltachat #desktop because we still had an old property key in our state reducer after a refactoring. github.com/deltachat/deltachat…

Refactor chat_scroll to be immutable by Jikstra · Pull Request #2968 · deltachat/deltachat-desktop

Fixes #2956 Fixes #2953

^GitHub

treefit reshared this.

in reply to Jikstra

In other words, the bug where desktop (test version 1.33) kept scrolling to the top of a chat is solved now thanks to @jikstra.
That was one of the blocking bugs that are delaying the desktop 1.34 release.

#deltachat_desktop #deltachat