TypeScript Intermediate

Preview — 3 of 10 questions

What is a union type in TypeScript?

javascript

function format(value: string | number): string {
  return String(value);
}

AA type that merges two objects into one

BA type that converts values automatically between types

CA type that requires all properties from two interfaces

DA type that means the value can be one of several specified types

Inside the if block, what is the inferred type of value?

javascript

function process(value: string | number) {
  if (typeof value === "string") {
    return value.toUpperCase(); // what type is value here?
  }
  return value * 2;
}

Astring

Bstring | number

Cnumber

Dunknown

What properties must an object of type Employee have?

javascript

type Person = { name: string; age: number };
type Worker = { company: string; role: string };
type Employee = Person & Worker;

AAll four: name, age, company, and role

BEither name/age or company/role — intersection means "choose one"

COnly the properties that appear in both types

DNo properties — Employee is an empty type

Answer all 10 questions (7 more), see explanations for every answer, and track your score.