How can you infer types from for loop values based on keys?

[pliant plume]

The Digital#3999

Playground Link

Preview:```ts
type objType = {
value1: string
number1: number
yes: string
}

const obj: objType = {
value1: "asfdasf",
number1: 912,
yes: "yes",
}

const newObj: objType = {
value1: "jkdfnvčleoknfgeokrg",
number1: 908543,
yes: "no",
...```

You can choose specific lines to embed by selecting them before copying the link.

[high pine]

you'd need to have the iterated thing have tuples with specific keys, not an array of all the k/vs there

you could use a mapped type for this

why do you need to though?

seems like either
a different structure would be better
or
you already know the shape of your objects, so a loop isn't really necessary

[dense nimbus]

my final goal is basically to update one object with another checking "each/most" properties before updating

[high pine]

checking "each/most" properties
uh, what?

im confused

[dense nimbus]

most of values*

[high pine]

from your playground, you know the shape though

[dense nimbus]

i do but i would need types inferred because

[dense nimbus]

and tbh i dont know where to put anything generic in for..of

[high pine]

you know the shape, do you really need the loop

[dense nimbus]

uhm

either loop or 10 if's

[high pine]

the loop still has those 10 ifs

[dense nimbus]

yes but looks nicer in switch

[high pine]

or if the loop helps with the ifs, then you can do just fine with a helper function

[high pine]

if you're saying the switch is the if, uh you don't need a switch either

[dense nimbus]

now im bit confused

[high pine]

const obj = {
  a: 0,
  b: "1"
};

for (const [k, v] of Object.entries(obj)) {
  switch (k) {
    case "a":
      console.log(v + 1);
      break;
    case "b":
      console.log(parseInt(v) + 1);
      break;
  }
}

// or

console.log(obj.a + 1);
console.log(parseInt(obj.b) + 1);

[high pine]

sorry wrote wrong word

[dense nimbus]

but that wont work

because if i want to assign or do some actions such as regex checking, it will say i cant do that on object

[dense nimbus]

because it treats it as object

[high pine]

...why do you want to use a regex on an object?

how would using a for..of/switch solve that

[dense nimbus]

i dont...

[high pine]

im so confused

[dense nimbus]

understandable

so

[dense nimbus]

if i do for loop on such ^ object, type of value will be shown as any of those values in type right?

[high pine]

yeah

[dense nimbus]

so now i wanna do a switch which would fix that and if i have a case 'button', in that case, value will be treated as string

same as for if i do case 'uptimeLogs', value inside will be treated as that object

[high pine]

why can't you just do obj.button and know it's a string

without the loop+switch

[dense nimbus]

i can but then i would has 10 if's as said earlier

[high pine]

how?

[dense nimbus]

if (obj.button) {}
if (obj.message_id) {}
if (obj.role_mention) ...

[high pine]

no wtf

what?

[dense nimbus]

what

[high pine]

no just do obj.button

[dense nimbus]

but i need for multiple properties lol

[high pine]

what would those ifs be doing?

[high pine]

yeah... so access multiple properties

you don't need ifs for that

[dense nimbus]

what

[high pine]

for (const [key, value] of ...) {
  switch (key) {
    case "button":
      someFunctionUsingString(value);
      break;
    ...
  }
}
```suppose this as a placeholder for your proposed loop, does this make sense

[high pine]

module.button = body.button ?? null;???

[dense nimbus]

and what if body.button is random string

[high pine]

it shouldn't be to begin with?

are these inputs unsafe

[dense nimbus]

yes

[high pine]

i see the issue

[dense nimbus]

rest route for updating

[high pine]

module.button = body.button?.match(...) ? body.button : null

why not this then

[dense nimbus]

because

uh

well

isnt that just same as if

[high pine]

you'd need some form of if on the condition here anyways

[dense nimbus]

in more compact way

[high pine]

yes

using a loop and switch would just be obfuscation, considering you need ifs afterwards

[dense nimbus]

yeah

well good to know

thanks tho lol

[high pine]

also Object.entries isn't typesafe but that wouldn't have mattered in the context given, it'd just be annoying to convince ts

[dense nimbus]

i noticed that

[dense nimbus]

basically this but yeah

[high pine]

i don't think the initial check is required there

that's what ?. does

https://justlink.to/mdn/optional_chaining

[dense nimbus]

yeah i know, but does it really change anything

[high pine]

makes it less readable i'd argue

optional chaining or separate check

having both is confusing

to me, at least

[dense nimbus]

well ill make it with ?. but true

[dense nimbus]

this is off topic but what if i just check the request origin... if its not from my dash url, deny it

that way i can have safe input

[high pine]

idk networking, no clue if that's safe

[dense nimbus]

rip

[high pine]

wait isn't this just cors

am i tripping

[dense nimbus]

what

[high pine]

or is that on the other side

[dense nimbus]

wait