// original type
type Bird = {
  name: string;
  hasWings: boolean;
  hasLegs: boolean;
  color: string[];
  fly: () => void;
};

// pick (select a few)
type SubBird = Pick<Bird, "name" | "hasLegs">

// omit (unselect a few)
type UnnamedBird = Omit<Bird, "name">

// is ()
function isBird(t: any): t is Bird {
	...
};

Pick Type

Picks the set of properties defined from the original type.

// example from doc
interface Todo {
  title: string;
  description: string;
  completed: boolean;
}
 
type TodoPreview = Pick<Todo, "title" | "completed">;
 
const todo: TodoPreview = {
  title: "Clean room",
  completed: false,
};

Omit Type

Picks all properties from the original type, then removes the defined key from the type.

Opposite of Pick.

// syntax
type OmittedType = Omit<TypeName, 'key_name'>

// example from doc
interface Todo {
  title: string;
  description: string;
  completed: boolean;
  createdAt: number;
}
 
type TodoPreview = Omit<Todo, "description">;
 
const todo: TodoPreview = {
  title: "Clean room",
  completed: false,
  createdAt: 1615544252770,
};