[This post is part of a series on JavaScript quirks.]

Closures are a powerful JavaScript feature: If a function leaves the place where it was created, it still has access to all variables that existed at that place. This blog post explains how closures work and why one has to be careful w.r.t. inadvertent sharing of variables.

Web Components [1] are an upcoming standard for custom HTML5 user interface elements. Those UI elements will eventually become interchangeable between frameworks. Now the people behind AngularJS and Ember.js have described their plans for supporting Web Components.

Updates:

• [2013-07-16] Hello Polymer: Q&A with Google’s Polymer team [more information on Polymer]
• [2013-05-23] Plans for supporting Web Components in AngularJS and Ember.js

At Google I/O 2013, Google presented a new web user interface (UI) framework called Polymer. The way it works is indicative of the future of all web UI frameworks.

[This post is part of a series on JavaScript quirks.]

In most programming languages, variables only exist within the block in which they have been declared. In JavaScript, they exist in the complete (innermost) surrounding function:

    function func(x) {
        console.log(tmp); // undefined
        if (x < 0) {
            var tmp = 100 - x;  // (*)
            ...
        }
    }

Two tweets by Brendan Eich shed light on the history of JavaScript having both undefined and null [1].

Current technology encourages us to be continuously connected. This blog post predicts that that will change.

[This post is part of a series on JavaScript quirks.]

The basics of parameter handling in JavaScript are simple, advanced tasks require manual work. This blog post first looks at the basics and then covers advanced topics.

[This post is part of a series on JavaScript quirks.]

Let’s start with a simple rule: the normal equality operators == and != are so problematic that you should always use strict equality (=== and !==). Some people say that there are exceptions to this rule, I disagree [2]. Keeping this rule in mind, we can now take a look at what is strange about ==, without burdening our minds unnecessarily.

There are several ways of checking whether a variable has the value undefined. This blog post explains the differences.