chapter_1.4.md

1.4 Generics/type programming

• Generics
  • Why is it better than any?
  • Use cases (useState<>, Component<>)
  • Create map using generics

Exercises

1. Create a generic function called filter that takes an array and a function and returns a new filtered array.

Example:

filter([1, 2, 3, 4], (element) => element % 2 === 0)  
// returns [2, 4]

filter([‘hello’, ‘world’, ‘cat’, ‘dog’, ‘cat’], (element) => element === ‘cat’)  
// returns [‘cat’, ‘cat’]