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JavaScript Tutorial

4. Literals

You use literals to represent values in JavaScript. These are fixed values, not variables, that you literally provide in your script. Examples of literals include: 1234, "This is a literal," and true.

4.1. Integers

Integers can be expressed in decimal (base 10), hexadecimal (base 16), and octal (base 8). A decimal integer literal consists of a sequence of digits without a leading 0 (zero). A leading 0 (zero) on an integer literal indicates it is in octal; a leading 0x (or 0X) indicates hexadecimal. Hexadecimal integers can include digits (0-9) and the letters a-f and A-F. Octal integers can include only the digits 0-7.
Some examples of integer literals are: 42, 0xFFF, and -345.

4.2. Floating-point literals

A floating-point literal can have the following parts: a decimal integer, a decimal point ("."), a fraction (another decimal number), an exponent, and a type suffix. The exponent part is an "e" or "E" followed by an integer, which can be signed (preceded by "+" or "-"). A floating-point literal must have at least one digit, plus either a decimal point or "e" (or "E").
Some examples of floating-point literals are 3.1415, -3.1E12, .1e12, and 2E-12

4.3. Boolean literals

The Boolean type has two literal values: true and false.

4.4. String literals

A string literal is zero or more characters enclosed in double (") or single (') quotation marks. A string must be delimited by quotation marks of the same type; that is, either both single quotation marks or double quotation marks. The following are examples of string literals:

  • "blah"
  • 'blah'
  • "1234"
  • "one line \n another line"
In addition to ordinary characters, you can also include special characters in strings, as shown in the last element in the preceding list. The following table lists the special characters that you can use in JavaScript strings.
Character Meaning
\b backspace
\f form feed
\n form feed
\r carriage return
\t tab
\\ backslash character

4.5. Escaping characters

For characters not listed in the preceding table, a preceding backslash is ignored, with the exception of a quotation mark and the backslash character itself.
You can insert quotation marks inside strings by preceding them with a backslash. This is known as escaping the quotation marks. For example,
var quote = "He read \"The Cremation of Sam McGee\" by R.W. Service."
document.write(quote)

The result of this would be
He read "The Cremation of Sam McGee" by R.W. Service.
To include a literal backslash inside a string, you must escape the backslash character. For example, to assign the file path c:\temp to a string, use the following:
var home = "c:\\temp"