jsFiddle is the perfect solution; it provides a custom environment (based on user selections) to test (or fiddle with) your JavaScript, HTML, and CSS code ... one of the examples — Delayed ...

Key Takeaways Top 2025 books teach HTML, CSS, JavaScript, and React for front-end mastery.Guides cover Node.js, databases, ...

Essentially, we get a more granular HTML syntax, which can just load segments instead of whole pages, and can submit Ajax requests. This is an interesting example of the DRY principle in action.