In most JavaScript engines, there is a global object console with methods for logging and debugging. That object is not part of the language proper, but has become a de facto standard, since being pioneered by the Firebug debugger. Since their main purpose is debugging, the console methods will most frequently be used during development and rarely in deployed code.

This blog post gives an overview of the methods of console.

Update 2014-02-08: Follow-up blog post “What are integers in JavaScript?”

JavaScript can only safely represent integers i in the range −2⁵³ < i < 2⁵³. This blog post examines why that is and what “safely represent” means. It is based on an email by Mark S. Miller to the es-discuss mailing list.

In web browsers, window refers to an object that contains the global variables. This blog post explains how it works and when to use it.

Update 2013-09-29: New sections 4.1 (“Matching any code unit”) and 4.2 (“Libraries”).

This blog post is a brief introduction to Unicode and how it is handled in JavaScript.

The ECMAScript Internationalization API is a standard JavaScript API that helps with tasks related to internationalization: collation, number formatting, date and time formatting. This blog post gives a brief overview and points to more reading material.

If there are a lot of tabs open in Google Chrome, it tends to become slow. Killing tabs by hand, via the Task Manager helps, but is tedious. The following bash script (by Sindre Sorhus) lets you conveniently kill all open tabs from the shell (OS X only):

Update 2013-09-14: New sections 1.2, 2 and 3.

This blog post explains when you should and should not put data in prototype properties.

This blog post examines JavaScript‘s type system. It answers questions such as: Is JavaScript dynamically typed? Weakly typed? What is coercion?

This blog post is a quick refresher of how objects can be protected in JavaScript. There are three levels of protection:

1. Preventing extensions is the weakest level,
2. sealing is stronger,
3. freezing is strongest.

In JavaScript, all objects are truthy [1], even new Boolean(false), empty arrays and empty objects:

    > Boolean(new Boolean(false))
    true
    > Boolean([])
    true
    > Boolean({})
    true

That is different from how objects are converted to number and string, where you can control the result by implementing the methods valueOf() and toString() [2].