Function has

modules/katamari/src/main/ts/ephox/katamari/api/Obj.ts:103–104

(obj: T, key: K)

};

export const has = <T extends {}, K extends keyof T>(obj: T, key: K): boolean =>
  hasOwnProperty.call(obj, key);

export const hasNonNullableKey = <T extends {}, K extends keyof T>(obj: T, key: K): obj is T & Record<K, NonNullable<T[K]>> =>
  has(obj, key) && obj[key] !== undefined && obj[key] !== null;