Literals (JavaScript: The Definitive Guide, 4th Edition)

2.6. Literals

A literal is a data value that appears directly in a program. The following are all literals:

12               // The number twelve
1.2              // The number one point two
"hello world"    // A string of text
'Hi'             // Another string
true             // A boolean value
false            // The other boolean value
/javascript/gi   // A "regular expression" literal (for pattern matching)
null             // Absence of an object

In ECMAScript v3, expressions that serve as array and object literals are also supported. For example:

{ x:1, y:2 }    // An object initializer
[1,2,3,4,5]     // An array initializer

Note that these array and object literals have been supported since JavaScript 1.2 but were not standardized until ECMAScript v3.

Literals are an important part of any programming language, as it is impossible to write a program without them. The various JavaScript literals are described in detail in Chapter 3.