When passing an object to a logging function, util.inspect allows you to control the recursion depth that it prints an objects properties, and also add colors to the output.
This would be a configuration option for the console appender.
function formatLogData(logData) should be changed to function formatLogData(logData, config) and a config object should be passed through allowing customisation of the log data. config.inspect.color could allow you to change inspect settings here.
function formatLogData(logData, config)
It would also be useful to allow objects to be pretty printed without newlines.
we could have:
This would add colors for a start:
output += util.inspect(item, false, 2, true);
you could do this with the pattern layout with tokens, check out https://github.com/nomiddlename/log4js-node/blob/9fe32d06e30680b31a558fd96ed3bfe048da3051/examples/patternLayout-tokens.js
layouts use util.format now, so I think this one can be closed.