app.js

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

var tokens = nlp.tokenize("Eligibility: Open to the general public, must have a library card to checkout library materials");

console.log(tokens.tag());
//Outputs "Open" as "NNP"

var tokens = nlp.tokenize("Eligibility: open to the general public, must have a library card to checkout library materials");

console.log(tokens.tag());
//Outputs "open" as "JJ"

nlp.js

var pos = require('pos');
var _ = require('lodash');

module.exports = {
	tokenize: function (string) {
		this.tokens = new pos.Lexer().lex(string);
		return this;
	},
	tag: function (tokens) {
		if (!tokens) {
			var tokens = this.tokens;
		}
		var taggedTokens = [];
		_.each(new pos.Tagger().tag(tokens), function(taggedToken) {
			var taggedToken = {
				token: taggedToken[0],
				tag: taggedToken[1]
			}
			taggedTokens.push(taggedToken);
		});
		return taggedTokens;
	}
}