Testable JavaScript

Colophon

The animal on the cover of Testable JavaScript is the Doctor fish (Acanthurus chirurgus), a tropical fish that can be found in shallow coral reefs throughout the Atlantic Ocean, especially around Massachusetts, the Caribbean, Brazil, and the west coast of Africa. It is the most wide-ranging fish within its genus. All members of the Acanthuridae family are distinctive for the sharp spines on either side of their tail fin—and in fact, Acanthurus is derived from the Greek for “thorn tail.” The common name of Doctor fish perhaps arose from these scalpel-like appendages, which the fish can use for defense against predators or other Doctor fish with a rapid side sweep of their tail.

This fish grows to be around 40 cm in length and is typically a blue or brown color. Despite the variations in color, all Doctor fish have 10-12 vertical bars on their body. Its teeth are specially shaped so that the fish can scrape algae and plant matter from rocks; it spends most of the day “grazing” in this manner. At times, Doctor fish will also consume sand, which helps grind food during the digestive process.

Doctor fish spawn within 24 hours after fertilization, and look like floating plankton for a short time. The fish does not typically grow its scalpels until it is around 13 mm in length. It reaches sexual maturity after 9 months. 

The cover image is from a loose plate, source unknown. The cover font is Adobe ITC Garamond. The text font is Adobe Minion Pro; the heading font is Adobe Myriad ...