Hopefully this is a simple enough question but I am having trouble figuring out how to word it in the title. I was making a function that gets and sets a value. And for the setting of the value I basically have to rewrite the initial type but with a question mark next to it because I will be automatically merging the current variables with the new ones.
Is there a simpler approach that allow you to dynamically add the question mark to this or is this the way to go about it? Because I want the original variables to be required in the Vars type.
So a simple example like:
interface Vars {
a: number
b: number
}
interface NewVars {
a?: number
b?: number
}
const createVars = () => {
let vars: Vars = {
a: 1,
b: 2
}
const get = () => vars
const set = (newVars: NewVars) => {
vars = {
...vars,
...newVars
}
}
return {
get,
set
}
}
You can use the Partial utility type
interface NewVars extends Partial<Vars> {}
//Or
const set = (newVars: Partial<Vars>) => {...}
See this on TS Playground
If you only want to add ? to certain values, just intersect the partial of the optional keys and required keys.
type PickOptional<T extends Record<any, any>, Opt extends string> = Partial<Pick<T, Opt>> & Omit<T, Opt>
// or doing the inverse
type PickRequired<T extends Record<any, any>, Req extends string> = Required<Pick<T, Req>> & Omit<T, Req>
interface NewVars extends PickOptional<Vars, 'a'> {}