Update 2014-08-04: Comprehensions won’t be in ECMAScript 6. There’s a chance that an updated version of them will be in ECMAScript 7 or later.

ECMAScript.next will have two kinds of comprehensions: array comprehensions and generator comprehensions. They allow one to quickly assemble an array or a sequence of elements. Comprehensions exist in many programming languages, for example: CoffeeScript, Python, Haskell, Clojure.

In languages whose syntax is derived from C (e.g.: C ← C++ ← Java ← JavaScript), two brace styles are most common: Allman style and 1TBS.

In JavaScript, there is an unfortunate overloading of the term “prototype”.

2012 has been a very productive JavaScript year for me:

I’m a big fan of blogs. After all, I’m writing one, myself. They are the contemporary version of a specialized newspaper. Regularly having new content is exciting and reading blogs is well supported by various apps, thanks to standardized publication formats such as RSS and Atom.

Update 2012-12-27: Better example for aliasing in Sect. 1.

In a blog post, David Walsh mentions two approaches for emptying (clearing) an array. This blog post explains the pros and cons of both approaches. In order to understand them, we first need to know about aliasing.

ECMAScript 6 [1] will bring many new features to the language. However, it will be years before we can rely on it being supported in most browsers that are in use. This post examines tools that will allow us to program with ECMAScript 6 much sooner.

The following puzzle has been posted on Reddit by davvblack: What are the values of x and y, given the following interaction?

    > x === y
    true
    > 1/x > 1/y
    true

ECMAScript 6 template strings [1] give us multi-line raw (backslash has no special meaning) string literals and interpolation. But they can also be tagged, in which case a library can determine the meaning of their content. Steven Levithan has recently given an example of how they could be used for his regular expression library XRegExp.