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JavaScript has long been the de facto choice for client-side web development, but lately its been catching on server-side as well. While we like to think that Apps Script has contributed to the trend, projects such as Mozillas Rhino and Node.js have also done a great deal to popularize the concept. As a result, developers have created a wealth of new open-source JavaScript libraries, and in this post well talk about how you can leverage them in your Apps Script projects.

Underscore
One library I wanted to use in my scripts was Underscore, which describes itself as "a utility-belt library for JavaScript." It provides a wealth of helper functions that make coding in JavaScript cleaner and more enjoyable. Take, for example, the simple situation where you want to log each value in a range.

// Using plain JavaScript.
for (var i = 0; i < values.length; i++) {
  for (var j = 0; j < values[i].length; j++) {
    Logger.log(values[i][j]);
  }
}

Although writing for loops like this is a common pattern, its a fair amount of typing and you need to keep track of counter variables that serve little purpose. Underscore provides an each() method that makes the process much simpler.

// Using Underscore.
_.each(values, function(row) {
  _.each(row, function(cell) {
    Logger.log(cell);
  });
});

Passing anonymous functions as parameters takes a little getting used to, but if youve worked with jQuery, the pattern feels familiar.

Underscore also has some great extensions, and Underscore.string provides some useful string manipulation features. My favorite is the ability to use sprintf() notation in JavaScript, which can simplify the process of building complex strings.

// Using plain JavaScript.
var message = "Hello, " + firstName + " " + lastName + ". Your wait time is " + wait + " minutes.";

// Using Underscore.string.
var message = _.sprintf("Hello, %s %s. Your wait time is %d minutes.", firstName, lastName, wait);

Integrating with Apps Script
The simplest way to include the Underscore library in a project would be to paste its source code directly into your script, but this would lead to a lot of duplication if you end up using it in multiple projects. Earlier this year, we released a feature in Apps Script called libraries that allows you to share scripts and include them in other projects. Packaging a JavaScript library like Underscore as an Apps Script library is possible, but requires some helper functions to work correctly.

When Underscore loads, it creates a global variable named "_" that you use to access its functionality. Apps Script specifically prevents the global scope of a library from interfering with the global scope of the script that includes it, so I built a helper function into the library to pass the variable around.

// In the library.
function load() {
  return _;
}

In my script that includes the library, I simply make a call to that function and use the result to set up my own "_" variable.

// In the script that includes the library.
var _ = Underscore.load();

To try my copy of the Underscore library in your own project, use the project key "MGwgKN2Th03tJ5OdmlzB8KPxhMjh3Sh48" and the code snippet above. You can browse the full source code here.

Using it with the HtmlService
Using the code above, I could easily include the library in my server-side Apps Script code, but I also wanted to use these functions client-side in my web app served by the HtmlService. To accomplish this, I created a copy of the Underscore source code, wrapped it in <script> tags, and stored them in Html files (instead of Script files). These snippet files could then be included in my web apps HtmlTemplates using the helper function below.

// In the library.
var FILES = [Underscore.js, Underscore.string.js, Init.js];
function include(output) {
  for (var i = 0; i < FILES.length; i++) {
    var file = FILES[i];
    output.append(
        HtmlService.createHtmlOutputFromFile(file).getContent());
  }
}

This function was called in the web apps HtmlTemplate using the simple code below.

<!-- In the web app that includes the library. -->
<html>
  <head>
    <? Underscore.include(output) ?>
  </head>
  ...

Other libraries
Integrating with Underscore was fairly easy, but trying the same approach with other open-source libraries may be a bit more complicated. Some libraries wont run correctly in the Apps Script environment if they rely on certain capabilities within the browser or Node.js runtime. Additionally, to be served by the HtmlService, the code must pass the Caja engines strict validation, which many popular libraries dont meet. In some cases, you may be able to manually patch the library to work around these issue, but this usually requires a deep understanding of how the library works.

We hope youre inspired to use Underscore and other open-source libraries in your own work. If you find a library that works great with Apps Script, share it with me on Google+ and Ill help get the word out.

Eric Koleda profile Eric is a Developer Programs Engineer based in NYC on the Google Apps Script team. Hes previously worked with the AdWords API and enterprise content management software.

Link to full article

"In muted tones, Microsoft?s chairman (Bill Gates) warned governments and companies that open source software is not the way to go if they are in the business of creating jobs and intellectual property. "

Below are Tony Bailetti, Ph.D. comments on the article about Mr. Gates speech in Asia.

1. Bill Gates is correct when he says that open source does not create jobs. He was, I am sure, referring to open source jobs in Puget Sound, Washington State, USA. This is the place where the bulk of Microsofts employees work. Surely Bill Gates knows that open source is creating thousands of jobs all over the world. Today, IBM and many of the largest companies in the world employ thousands of people to work on open source projects and fund hundreds of external open source projects that employ many more thousands of people. IBM and other companies have made millions, if not billions, from open source. In addition, many non-profit organizations such as governments, associations, universities, etc. all over the world pay people to develop open source software, install it, maintain it, support it, extend it, fix it, etc. Hundreds of small companies and individuals generate income thanks to open source. Worldwide people are creating wealth thanks to a business model enabled by open source. I agree that relatively few of these open source jobs have been created in Microsofts Puget Sound, Washington State, USA. This is quite unfortunate for Puget Sound.
   
2. Bill Gates is correct when he says that open source does not create IP. He is obviously referring to the IP that people pirate (i.e., copy a Microsoft CD without paying for the CD). There is no incentive to pirate open source software. You can get it for free (or near free). The success of open source is not based on the protection of proprietary technology, however, Microsoft?s success is. Microsoft makes billions selling proprietary software. Open source does create a different type of IP. This threatens Microsofts business model. Open source shifts the IP from product to service (or a complementary product). In other words, the value does not reside in the software product; the value resides in the service (or in a proprietary product that complements the software. E.g., a book that carries inside a CD with open source software in an attempt to sell more books at a higher price). The open source model has emerged as a viable alternative to traditional proprietary software. Today, open source, not Sun, Oracle, IBM or any other company, is the most serious competitor to Microsoft.
   
3. Bill Gates is correct when he says that open source products do not guarantee upward compatibility. However, Microsofts products do not make this guarantee either.
   
4. Bill Gates is correct when he points out that Windows has contributed to the Asian economy. However, so has open source! There is an important difference between Microsoft?s contribution to Asians and open source software?s contribution to Asians. The contribution to the Asian economy that open source has made will never make Asians dependent on the software from an American supplier headquartered in Washington State, USA.
   
5. Bill Gates is correct when he says that open source is developed at night and not during the day. You see, when its night time in Puget Sound, its day time in many other places in this world where people are busy developing high quality open source software.