JavaScript

19A Look Ahead …

WHAT'S IN THIS CHAPTER?

• Top-Level await
• WeakRefs and cleanup callbacks
• RegExp match indices
• String.prototype.replaceAll
• Atomics.asyncWait
• Various syntax changes
• Legacy deprecated RegExp features
• Thank you!

CODE DOWNLOADS FOR THIS CHAPTER

You can download the code for this chapter at https://thenewtoys.dev/bookcode or https://www.wiley.com/go/javascript-newtoys.

This final chapter follows on from the preview of upcoming class features in Chapter 18 with a preview of what else is coming next (features at Stage 3 as of this writing). But what's coming next is ever-changing. You can keep up to date using the resources you learned about in Chapter 1, including of course this book's website, https://thenewtoys.dev.

The changes and additions run the gamut from relatively minor (but handy) syntax tweaks like numeric separators to significant additions like top-level await.

Most in-progress features are covered here, though some have already been covered:

• A couple of upcoming promise utility features were covered in Chapter 8.
• import.meta was covered in Chapter 13.
• You just learned about public and private class fields and private methods and accessors (including static ones) in Chapter 18.

Some readers may be surprised not to see Decorators¹ covered in this chapter. Decorators have been in the proposals process for some time, and one version or another of the proposal is in wide use via transpilers and TypeScript. But the proposal is still at Stage ...