LITERALS

Types of literals:
• Array Literals
• Boolean Literals
• Floating-Point Literals
• Integers
• Object Literals
• String Literals


ARRAY LITERALS:


An array literal is a list of zero or more expressions, each of which represents
an array element, enclosed in square brackets ([]). When you create an array
using an array literal, it is initialized with the specified values as its elements,
and its length is set to the number of arguments specified.
The following example creates the coffees array with three elements and a
length of three:
coffees = ["French Roast", "Columbian", "Kona"]


BOOLEAN LITERALS:


The Boolean type has two literal values: true and false.
Do not confuse the primitive Boolean values true and false with the true and
false values of the Boolean object. The Boolean object is a wrapper around the
primitive Boolean data type. See “Boolean Object” on page 111 for more
information.


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
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 and
either a decimal point or “e” (or “E”).
Some examples of floating-point literals are 3.1415, -3.1E12, .1e12, and 2E-12


OBJECT LITERALS:


An object literal is a list of zero or more pairs of property names and associated
values of an object, enclosed in curly braces ({}). You should not use an object
literal at the beginning of a statement. This will lead to an error.
The following is an example of an object literal. The first element of the car
object defines a property, myCar; the second element, the getCar property,
invokes a function (Cars("honda")); the third element, the special
property, uses an existing variable (Sales).
var Sales = "Toyota";
function CarTypes(name) {
if(name == "Honda")
return name;
else
return "Sorry, we don’t sell " + name + ".";
}
car = {myCar: "Saturn", getCar: CarTypes("Honda"), special: Sales}
document.write(car.myCar); // Saturn
document.write(car.getCar); // Honda
document.write(car.special); // Toyota
Additionally, you can use an index for the object, the index property (for
example, 7), or nest an object inside another. The following example uses these
options. These features, however, may not be supported by other ECMAcompliant
browsers.
car = {manyCars: {a: "Saab", b: "Jeep"}, 7: "Mazda"}
document.write(car.manyCars.b); // Jeep
document.write(car[7]); // Mazda


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 both double quotation
marks. The following are examples of string literals:
• "blah"
• 'blah'
• "1234"
• "one line \n another line"
You can call any of the methods of the String object on a string literal value—
JavaScript automatically converts the string literal to a temporary String object,
calls the method, then discards the temporary String object. You can also use
the String.length property with a string literal.
You should use string literals unless you specifically need to use a String object.
See “String Object” on page 118 for details on String objects.