Lazy box

lazy-box.ts

function lazy<T>(getter: () => T): { value: T } {
  return {
    get value() {
      const value = getter();
      Object.defineProperty(this, "value", { value });
      return value;
    },
  };
}

const myValue = lazy(() => "hello world");
console.log(myValue.value); // computes value and overwrites getter
console.log(myValue.value); // returns cached value
console.log(myValue.value); // returns cached value