most typescript thing i've wrote, will update when things get worse

most-typescript-thing-ive-wrote.ts

type Category = {
  title: string;
  items: Array<{ name: string }>;
};

type Config = {
  categories: Record<string, Category>;
};

function isCategory(obj: unknown): obj is Category {
  return (
    typeof obj === 'object' &&
    obj !== null &&
    'title' in obj &&
    'items' in obj &&
    Array.isArray((obj as Category).items) &&
    (obj as Category).items.every(
      (item) => typeof item === 'object' && 'name' in item
    )
  );
}

function createWebsite<T extends Config>(config: T): void {
  Object.entries(config.categories).forEach(([key, category]) => {
    if (isCategory(category)) {
      console.log(`Category title: ${category.title}`);
      category.items.forEach((item, index) => {
        console.log(`Item ${index + 1}: ${item.name}`);
      });
    }
  });
}

javascript equivalent is something like:

function isCategory(obj) {
  return (
    typeof obj === 'object' &&
    obj !== null &&
    'title' in obj &&
    'items' in obj &&
    Array.isArray(obj.items) &&
    obj.items.every(
      (item) => typeof item === 'object' && 'name' in item
    )
  );
}

function createWebsite(config) {
  Object.entries(config.categories).forEach(([key, category]) => {
    if (isCategory(category)) {
      console.log(`Category title: ${category.title}`);
      category.items.forEach((item, index) => {
        console.log(`Item ${index + 1}: ${item.name}`);
      });
    }
  });
}