JavaScript

17Miscellany

WHAT'S IN THIS CHAPTER?

• BigInt
• Binary integer literals
• Octal integer literals, take II
• Optional catch bindings
• New Math methods
• Exponentiation operator
• Tail call optimization
• Nullish coalescing
• Optional chaining
• Other syntax tweaks and standard library additions
• Annex B: Browser-only features

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.

In this chapter, you'll learn about the various things that didn't really fit anywhere else in the book: BigInt, new forms of numeric literals; various new Math methods; the new exponentiation operator (and a “gotcha” about its precedence); tail call optimization (including why you can't rely on it, yet or possibly ever); some other minor changes; and finally, some browser-only features added to Annex B to document what's universally there anyway.

BIGINT

BigInt¹ is a new primitive type for working with large integers in JavaScript, added in ES2020.

BigInt can hold any size of integer, limited only by available memory and/or a reasonable limit imposed by the JavaScript engine's implementers. (Implementer limits are likely to be very, very high. V8 currently allows up to one billion bits.) Do you want to hold the number 1,234,567,890,123,456,789,012,345,678 (an integer with 28 significant digits) in a variable? JavaScript's normal number type (Number) can't begin to think about that, not precisely anyway; ...