union & intersection of types(@TypeScript)

// union & intersection of types
type Cat = {name: string, purrs: boolean}
type Dog = {name:string, barks: boolean}
type CatOrDog = Cat | Dog
type CatAndDog = Cat & Dog

let a_o: CatOrDog = {
    name: 'ball',   // need not to specify all properties
    barks: false
}

let a_a: CatAndDog = {
    name: "Dounald",
    barks: false,   // need to specify all properties of the Dog and Cat
    purrs: false
}