anagram_test.spec.js

var anagram = require('./anagram');

describe('Anagram', function() {

  it("no matches",function() {
    var subject = anagram("diaper");
    var matches = subject.matches([ "hello", "world", "zombies", "pants"]);

    expect(matches).toEqual([]);
  });
};

@scottluptowski, how can I make a JS object that can be initialized with an argument (in the above example that's the anagram("diaper") bit) and subsequently that object responds to another method matches which introspects the object's property where we stored the string "diaper" initially?

function Anagram (input) {
  this.input = input;
  this.matches = function () {
    // logic goes here...
  };
}

var anagram = function(input) {
  return new Anagram (input);
};

module.exports = anagram;

Nice! That's most of the way there.

The better approach to matches is to put on the prototype of the function.

function Anagram (input) {
  this.input = input;
}

Anagram.prototype.matches = function () {
    // logic goes here...
}