ipv4-range takes an IPv4 address and a number, and returns an array of surrounding addresses.
npm install ipv4-range
ipv4-range( ip (string): the starting ip address. total (int): the number of surrounding addressed you're interested in. Odd numbers will result in the results being weighted to the left, where possible. )
var range = require('ipv4-range') range('192.168.0.4', 3) // => ['192.168.0.2', '192.168.0.3', '192.168.0.5']