Closure Library 
Closure Library is a powerful, low-level JavaScript library designed for building complex and scalable web applications. It is used by many Google web applications, such as Google Search, Gmail, Google Docs, Google+, Google Maps, and others.
For more information, visit the Google Developers or GitHub sites.
Download the latest stable version on our releases page.
Developers, please see the Generated API Documentation.
See also the goog.ui Demos
Using with Node.js
Install the official package from npm.
npm install google-closure-library
Require the package and use goog.require normally.
require("google-closure-library");
goog.require("goog.crypt.Sha1");
var sha1 = new goog.crypt.Sha1();
sha1.update("foobar");
var hash = sha1.digest();