Private Field Presence Checks (TypeScript 4.5 Article)

privateFieldPresenceCheck.ts

class Person {
   #name: string;
   constructor(name: string) {
       this.#name = name;
   }
   equals(other: unknown) {
       return other &&
           typeof other === "object" &&
           #name in other && // <- this is new!
           this.#name === other.#name;
   }
}