libMinTest.js

var testFn = function() {};

testFn.prototype.test1 = function() {
    console.log('test1');
};

testFn.prototype.test2 = function() {
    console.log('test2');
};

var dead_code = function() {
    console.log('dead code');
}

module.exports = testFn;

testUse.js

var testFn = require('./libMinTest.js');

var test = new testFn();
test.test1();

for(var fn in test) {
    if(typeof(test[fn]) === 'function') {
        test[fn]();
    }
}

testUseBrowserify.js

(function e(t,n,r){function s(o,u){if(!n[o]){if(!t[o]){var a=typeof require=="function"&&require;if(!u&&a)return a(o,!0);if(i)return i(o,!0);var f=new Error("Cannot find module '"+o+"'");throw f.code="MODULE_NOT_FOUND",f}var l=n[o]={exports:{}};t[o][0].call(l.exports,function(e){var n=t[o][1][e];return s(n?n:e)},l,l.exports,e,t,n,r)}return n[o].exports}var i=typeof require=="function"&&require;for(var o=0;o<r.length;o++)s(r[o]);return s})({1:[function(require,module,exports){
var testFn = function() {};

testFn.prototype.test1 = function() {
    console.log('test1');
};

testFn.prototype.test2 = function() {
    console.log('test2');
};

var dead_code = function() {
    console.log('dead code');
}

module.exports = testFn;

},{}],2:[function(require,module,exports){
var testFn = require('./libMinTest.js');

var test = new testFn();
test.test1();

for(var fn in test) {
    if(typeof(test[fn]) === 'function') {
        test[fn]();
    }
}

},{"./libMinTest.js":1}]},{},[2]);