problems using the example

[ekelvin]

var digest = require('http-digest-client').createDigestClient('username', 'password');
throws an error.

1. you should change it in:
   var digest = require('http-digest-client')('username', 'password');
2. it throws an Error here:
   HTTPDigest.prototype._parseChallenge = function parseChallenge(digest) {
   var prefix = "Digest ";
   var challenge = digest.substr(digest.indexOf(prefix) + prefix.length);
   digest is undefined so you can't call indexOf

It throws the 2. error when you try to connect to an existing path route.

[dayuoba]

var digest = require('http-digest-client')('username', 'password');

[addshore]

Looks fixed in 1819fd3