Looking to derive the numerical length of a string:
type Length = LengthOfString<"hello">
// ^? should equal 5
Feeling a bit lost on how to approach this. Any guidance on how to achieve this?
(Currently diving into typescript's type system for learning purposes -- not intended for JS code)
In order to separate each character of a string, one approach is to utilize a template literal string. This method involves adding an element to the tuple L for every character that can be extracted from the string.
type LengthOfString<T extends string, L extends any[] = []> =
T extends `${string}${infer R}`
? LengthOfString<R, [...L, string]>
: L["length"]
Once all characters have been processed, the function returns the length of L.
Outcome:
type Length = LengthOfString<"hello">
// ^? 5
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