About the Author
Ethan Brown is Director of Engineering at Pop Art, a Portland-based interactive
marketing agency, where he is responsible for the architecture and implementation of
websites and web services for clients ranging from small businesses to international
enterprise companies. He has over 20 years of programming experience, from
embedded to the Web, and has embraced the JavaScript stack as the web platform of
the future.
Colophon
The animal on the cover of Learning JavaScript, Third Edition, is a baby black, or
hook-lipped, rhinoceros (Diceros bicornis). The black rhino is one of two African spe‐
cies of rhinos. Weighing up to one and a half tons, it is smaller than its counterpart—
the white, or square-lipped, rhinoceros. Black rhinos live in savanna grasslands, open
woodlands, and mountain forests in a few small areas of southwestern, south central,
and eastern Africa. They prefer to live alone and will aggressively defend their terri‐
tory.
With an upper lip that tapers to a hooklike point, the black rhino is perfectly suited to
pluck leaves, twigs, and buds from trees and bushes. It is able to eat coarser vegetation
than other herbivores.
Black rhinos are odd-toed ungulates, meaning they have three toes on each foot. They
have thick, gray, hairless hides. Among the most distinctive of the rhino’s features is
its two horns, which are actually made of thickly matted hair rather than bone. The
rhino uses its horns to defend itself against lions, tigers, and hyenas, or to claim a
female mate. The courtship ritual is often violent, and the horns can inflict severe
wounds.
After mating, the female and male rhinos have no further contact. The gestation
period is 14 to 18 months, and the calves nurse for a year, though they are able to eat
vegetation almost immediately after birth. The bond between a mother and her calf
can last up to four years before the calf leaves its home.
In recent years, rhinos have been hunted to the point of near extinction. Scientists
estimate that there may have been as many as a million black rhinos in Africa 100
years ago, a number that has dwindled to 2,400 today. All five remaining species,
which include the Indian, Javan, and Sumatran rhinos, are now endangered. Humans
are considered their biggest predators.
Many of the animals on O’Reilly covers are endangered; all of them are important to
the world. To learn more about how you can help, go to
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