Node.js script for creating an array of all unique keys in an array of Javascript objects.

allKeys.js

var _ = require('underscore')

function allKeys (In, Out) {
	for (var i = 0; i < In.length; i++) {
		var fieldArray = Object.keys(In[i])
		if (!(Out.some(function (b) { return _.isEqual(fieldArray, b)}))) {
			Out.push(fieldArray)
		}
	}
  var OutCombined = _.reduce(Out, function(a, b) { return a.concat(b); }, []);
  var OutUnique = _.uniq(OutCombined)
  return OutUnique
}