Upon hovering over the typeof for a random object property, we are presented with a range of potential types:
"string" | "number" | "bigint" | "boolean" | "symbol" | "undefined" | "object" | "function"https://i.sstatic.net/0qnKa.jpg
Is there a way to define that list as a custom type, without manually specifying each option like this:
type ObjectPropertyType =
string |
number |
bigint |
boolean |
symbol |
undefined |
object |
Function;
Typeof is a built-in function in JavaScript that provides the type of a variable at runtime as a string. However, TypeScript types differ from this and were intentionally made similar to JavaScript for ease of use.
For example, "string" | "number" and string | number are not equivalent. While values like "Hello" and 42 can be assigned to the latter, they cannot be assigned to the former.
It's important to note that Typeof only deals with JavaScript-defined types and has no direct relation to TypeScript. TypeScript focuses on understanding possible values to provide accurate typing.
So, in response to the query:
How can we define a custom type for that list?
These types inherently differ. For instance, typeof null === "object", meaning even the TypeScript type null would need to be included in that list. Ultimately, the list of types resulting in any value when applying typeof to a variable of that type is simply any. Hence,
type CustomType = any;
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