Intro to Generics 9 exercises

TypeScript Generics

Section Resources
- Generics section of the TypeScript docs
  The TypeScript docs for generics have info and examples on creating and using generic types.
- The unknown Type from the TypeScript Docs
  Learn more about the unknown type in the TypeScript docs
- Generic Constraints from the TypeScript Docs
  The "Generic Constraints" page from the TypeScript documentation provides detailed information on how to define constraints for generic types
- 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.
- gesture.ts from the Excalidraw GitHub Repo
  See a real-world example of how generics are used in a software project.
- Total TypeScript - The Extends Keyword in action
  A refresher from the Type Transformations workshop lesson, "Support Function Type Constraints with Variable Arguments", showing extends in action.

Transcript

0:00 We have another function here called returnBothOfWhatIPassIn, where we're taking this time as a params object, where you need to pass in an object where A is A and B is B. It's expecting to infer just exactly the same as the previous exercise where you have first as string and second as number.

0:19 A is being passed to first and B is being passed to second. Your job is to work out how to type this using generic syntax.

Problem

Approaches for Typing Object Parameters

Consider this implementation of returnBothOfWhatIPassIn:


const returnBothOfWhatIPassIn = (params: { a: unknown; b: unknown }) => {
  return {
    first: params.a,
    second: params.b,
  };
};

This time the function takes in a params object that includes a and b.

Chal

Transcript

0:19 A is being passed to first and B is being passed to second. Your job is to work out how to type this using generic syntax.