[TypeScript] Generics

What are K,T, and V in TypeScript Generics?

function foo <T>(value: T) : T {
	return value;
 }

• from the above example, the T is a generic type parameter which is a type placeholder we pass to the foo function.
• type can be chained to the parameter type and the return value type like (value: T) : T
• T is just a generic name for Type and can be replaced with any valid name.
  1) K(Key) : type of key on the object.
  2) V(Value) : type of value in the object.
  3) E(Element) : the element type.

more than one type parameters can be assigned as below.

function foo<T, U>(value: T, message: U): T {
	console.log(message);
    return value;
 }
 
 console.log(foo<number, string>(11, "콘솔로그")

• from the above example, when we call foo function inside our console.log number type is assigned to type T and it is passed to value and return type.
• we do not HAVE to specify the actual stype and let TypeScript automatically complete the type inference for us.