Passing Type Arguments 7 exercises

TypeScript Generics

Section Resources
- JavaScript Set from MDN
  MDN reference for the Set object in JavaScript, which is a collection of unique values.
- Classes section of the TypeScript docs
  The Classes section of the TypeScript docs provides detailed information on how to use generics with classes, including examples and best practices.
- Record Types from the TypesScript docs
  Documentation for the Record utility type in the TypeScript Handbook.
- TypeScript's reduce type signature from its source on GitHub
  TypeScript's reduce method signature on GitHub in the type declaration file used as a reference for JavaScript's built-in objects available in TypeScript.
- fetch, Response, and Body from TypeScript's DOM lib source on GitHub
  TypeScript's DOM lib provides the types for interacting with the Document Object Model.
- Awaited Utility Type from the TypeScript docs
  Documentation for the Awaited utility type in the TypeScript Handbook. This type can be used to extract the type of a Promise or Async value.
- Sengrid.ts from the Cal.com Github Repo
  A TypeScript class for interacting with the SendGrid email service in the cal.com repository.

Transcript

0:00 This exercise starts where the previous exercise ended, where we have a createSet function, which is passing our generic into our Set here, and this works for number and for string. Now, instead of expecting this one to be unknown -- Set<unknown>, rather -- we're actually expecting it to be Set<string>.

0:21 Your job is to try and work out what the default or how to specify a default in this whole setup so that when we don't pass the type argument here, it gets resolved as string.

Problem

Defaults in Type Parameters

Let's continue from where the previous exercise left off.

We have the createSet function that passes the generic T into a Set:


export const createSet = <T>() => {
  return new Set<T>();
};

Like before, the numberSet and stringSet work as expected:


const nu

Transcript

0:21 Your job is to try and work out what the default or how to specify a default in this whole setup so that when we don't pass the type argument here, it gets resolved as string.