title: Model.Find() - How to return array of ObjectId
body: <p>I have an array of category titles. I want to make function return an array of <code>ObjectId</code> from these titles. How can I do it?</p>
  
  <pre><code>Category Model: {_id, title}
  
  
      const findCategoryIdsFromCategoryTitles = (titles) =&gt; {
          return Category.find({ title: { $in: titles } })._id
      }
  
      let titles = ["A1", "A2", "A3"]
      let categoryIds = findCategoryIdsFromCategoryTitles(titles)
  </code></pre>