[Typescript] Filtering properties out
List all the props with begin with "query" key in Document
type queryTypes = Extract<keyof Document, `query${string}`>
type queryyPoprDoc = {
[Key in queryTypes]: Document[Key]
}
What if we want to filter out by value?
For example we want to get all the methods which return Element | Element[]
.
Idea:
- Construct kind of object:
{
querySelector: "querySelector",
alinkColor: never
..
}
-
So in the object type, anything which return
Element | Element[]
, will keep the key as string, otherwise will assignnever
type. -
Get all the string value out of the object type
type FilteredKeys<TValue, Condition> = {
[K in keyof TValue]: TValue[K] extends Condition ? K: never
}[keyof TValue] & keyof Document
type RelevantDocumentKeys = FilteredKeys<Document, (...args: any[]) => Element | Element[]>
type ValueFilteredDoc = Pick<Document, RelevantDocumentKeys>
function load(doc: ValueFilteredDoc) {
doc.querySelector("input")
}