JavaScript: The Definitive Guide, 6th Edition

Numbers

Unlike many languages, JavaScript does not make a distinction between integer values and floating-point values. All numbers in JavaScript are represented as floating-point values. JavaScript represents numbers using the 64-bit floating-point format defined by the IEEE 754 standard,^[1] which means it can represent numbers as large as ±1.7976931348623157 × 10³⁰⁸ and as small as ±5 × 10⁻³²⁴.

The JavaScript number format allows you to exactly represent all integers between −9007199254740992 (−2⁵³) and 9007199254740992 (2⁵³), inclusive. If you use integer values larger than this, you may lose precision in the trailing digits. Note, however, that certain operations in JavaScript (such as array indexing and the bitwise operators described in Chapter 4) are performed with 32-bit integers.

When a number appears directly in a JavaScript program, it’s called a numeric literal. JavaScript supports numeric literals in several formats, as described in the following sections. Note that any numeric literal can be preceded by a minus sign (-) to make the number negative. Technically, however, - is the unary negation operator (see Chapter 4) and is not part of the numeric literal syntax.

Integer Literals

In a JavaScript program, a base-10 integer is written as a sequence of digits. For example:

0
3
10000000

In addition to base-10 integer literals, JavaScript recognizes hexadecimal (base-16) values. A hexadecimal literal begins with “0x” or “0X”, followed by a string of hexadecimal digits. A hexadecimal ...