Can someone please help me decipher this code snippet I found in a file? I'm completely lost as to what it is trying to accomplish.
const user = rowData as NonNullable<ApiResult["getUsers"]["data"][number]["users"]>[number];
I am baffled by how a type (number) can be used to access an object property. It's worth noting that `ApiResult` is a type generated by graphql and this code is located within a `renderCell` function for an array of `GridColumns` in an mui data grid.
How can you access an object's property using a number in TypeScript?
In TypeScript, an array is considered an object with values stored at numbered keys. Therefore, to access the type of each element in the array, you would use ArrayType[number].
NonNullable<Type> creates a type by removing null and undefined from the original Type.
An example is provided below demonstrating the data structure extension with a hypothetical User type. You can explore IntelliSense suggestions for types A to F by visiting the TS Playground link:
type User = {
one: 'This is';
two: 'the targeted type';
};
type ApiResult = {
getUsers: {
data: Array<{
users: Array<User> | null | undefined;
}>;
};
};
declare const rowData: unknown;
const user = rowData as NonNullable<ApiResult["getUsers"]["data"][number]["users"]>[number];
// examine hierarchy:
type A = ApiResult
type B = ApiResult["getUsers"]
type C = ApiResult["getUsers"]["data"]
type D = ApiResult["getUsers"]["data"][number]
type E = ApiResult["getUsers"]["data"][number]["users"]
type F = NonNullable<ApiResult["getUsers"]["data"][number]["users"]>[number]
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