index.js

var cmd = require("cmd.js"),
	truncate = require("./truncate");

cmd.module('truncate', truncate);

var articles = [
	{ title: "Lorem ipsum dolor sit amet, musis nihilominus admonendus tu tu", body : "Lorem ipsum dolor sit amet, caelum levaverunt te finis puellam. Aderit omnia salva deus Hellenici silentio flebam terris classes nostram."},
	{ title: "My first article", body: "Ego esse ait mea Christianis, concursus male nuptiarum civibus nescis. Quos ducem cum magna duobus discessit de me in deinde cupis ei."},
	{ title: "My second article post", body : "Mansione sed eu fugiens laudo in, zurziaca in fuerat construeret cena. Nubila grata gratias eos est Apollonius in modo invenit nutricis actum in lucem."},
	{ title: "This is just an article", body : "Filiam sunt amore tolle quae non potentiae cognoscitivarum non ait. Neminem habere matrem Domini in fuerat eum filiam rex Dionysiadi rex Dionysiadi rex in modo ad per sanctus primum subsannio."}
];

cmd.get('body').
	and.truncate(30).
	and.log(articles);
	
cmd.get('title').
	and.truncate({size: 10}).
	and.log(articles);

truncate.js

// truncate command for : https://github.com/NateFerrero/cmd.js
(function () {
    'use strict';
	
    this.export = function () {
		
		/**
         * Command: truncate(size)(String) - truncates a string
         * Command: truncate({ size: Number})(String) - truncates a string
         * @author Zikani Nyirenda Mwase
         */
		this.each = function (args, val) {
			var len = 10;
			var _arg = args[0];
			
			if (typeof _arg === 'number') {
				len = _arg;
			}
			
			len = _arg.hasOwnProperty('size') ? _arg.size : len;
			
			if (len >= val.length) {
				len = val.length;
			}
			
			return val.substring(0, len) + '...';
		};	
	};
}).call(typeof module === 'undefined' ? this['cmd:lib'].add = {} : this);

truncate.spec.js

var cmd = require('cmd.js'),
    truncate = require('./truncate'),
    expect = require('chai').expect;

/**
 * Add the command to the global cmd Command
 */
cmd.module('truncate', truncate);

/**
 * Tests
 */
describe('cmd.truncate', function () {

    it('is a function', function () {
        expect(cmd.truncate).to.be.a('function');
    });

    it('truncates a string to the specified length', function () {
        expect(cmd.truncate(2)("Hello")).to.deep.equal(["He..."]);
        expect(cmd.truncate(3)("Hello")).to.deep.equal(["Hel..."]);
    });

});