High Performance JavaScript

Colophon

The animal on the cover of High Performance JavaScript is a short-eared owl (Asio flammeus). As its name suggests, the bird’s signature ear tufts are small and appear simply as ridges on the top of its large head. These tufts become more visible, however, when the owl feels threatened and enters a defensive pose. A medium-sized owl, the bird has yellow eyes, mottled brown plumage with a pale, streaked chest, and dark bars on its broad wings.

One of the world’s most widespread avian species, this is a migratory bird that can be found on every continent except Australia and Antarctica. The short-eared owl lives in open country, such as prairies, marshland, or tundra. It catches small mammals like voles (and the occasional bird) either by flying low to the ground or by perching on a short tree, then diving on its prey. The owls are most active at dawn, late afternoon, and dusk.

The flight of the short-eared owl is frequently compared to that of a moth or bat, as it moves back and forth with slow, irregular wing beats. During breeding season, males exhibit spectacular aerial courtship displays in which they clap their wings together, rise in circles to great heights, and dive rapidly toward the ground. The short-eared owl is also somewhat of a thespian in the animal world—it will play dead to avoid detection, or feign a crippled wing to lure predators away from its nest.

The cover image is from Cassell’s Natural History. The cover font is Adobe ITC Garamond. The text font is Linotype ...