Introduction to CoffeeScript

CoffeeScript is a programming language that trans-compiles to JavaScript. It adds syntactic sugar inspired by Ruby, Python and Haskell in an effort to enhance JavaScript’s brevity and readability. Specific additional features include list comprehension and pattern matching.

CoffeeScript support is included in Ruby on Rails version 3.1 and Play Framework. In 2011, Brendan Eich referenced CoffeeScript as an influence on his thoughts about the future of JavaScript.

On December 13, 2009, Jeremy Ashkenas made the first Git commit of CoffeeScript with the comment: “initial commit of the mystery language.” The compiler was written in Ruby. On December 24, he made the first tagged and documented release, 0.1.0. On February 21, 2010, he committed version 0.5, which replaced the Ruby compiler with a self-hosting version in pure CoffeeScript. By that time the project had attracted several other contributors on GitHub, and was receiving over 300 page hits per day.

On December 24, 2010, Ashkenas announced the release of stable 1.0.0 to Hacker News, the site where the project was announced for the first time.

On September 18, 2017, version 2.0.0 was introduced, which “aims to bring CoffeeScript into the modern JavaScript era, closing gaps in compatibility with JavaScript while preserving the clean syntax that is CoffeeScript’s hallmark.”

Almost everything is an expression in CoffeeScript, for example ifswitch and for expressions (which have no return value in JavaScript) return a value. As in Perl, these control statements also have postfix versions; for example, if can also be written after the conditional statement.

Many unnecessary parentheses and braces can be omitted; for example, blocks of code can be denoted by indentation instead of braces, function calls are implicit, and object literals are often detected automatically.

The CoffeeScript compiler has been written in CoffeeScript since version 0.5 and is available as a Node.js utility; however, the core compiler does not rely on Node.js and can be run in any JavaScript environment. One alternative to the Node.js utility is the Coffee Maven Plugin, a plugin for the popular Apache Maven build system. The plugin uses the Rhino JavaScript engine written in Java.

The official site at CoffeeScript.org has a “Try CoffeeScript” button in the menu bar; clicking it opens a modal window in which users can enter CoffeeScript, see the JavaScript output, and run it directly in the browser. The js2coffee site provides bi-directional translation.

The latest additions to CoffeeScript are as follows:

  • Source maps allow users to de-bug their CoffeeScript code directly, supporting CoffeeScript tracebacks on run time errors.
  • CoffeeScript supports a form of Literate Programming, using the .coffee.md or .litcoffee file extension. This allows CoffeeScript source code to be written in Markdown. The compiler will treat any indented blocks (Markdown’s way of indicating source code) as code, and ignore the rest as comments.

The above is a brief about CoffeeScript. Watch this space for more updates on the latest trends in Technology.

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