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Variables

You will probably recognize some of these keywords as reserved words in ECMAScript Edition 3, which

is why they are reserved.

Additionally, the proposal asks for the following reserved words:

abstract debugger enum

goto

implements interface

native

protected synchronized throws transient

volatile

As you can see, this list of reserved words clearly shows the Netscape proposal moving ECMAScript

more towards a Java-like syntax.

The following words were reserved in ECMAScript Edition 3, but are used as part of the language in

Netscape’s proposal:

boolean byte char double final float int long short static

Finally, special meanings are attached to the words

get

and

set

, which cannot be used as variable names.

Variables

According to the Netscape proposal, variables can be defined with an explicit type by including a semi-

colon and the type name when defining the variable, like this:

var color : String = “red”;

In the previous code, a variable with name

color

is created as type

String

. Defining the type for a vari-

able is optional under this proposal. This can also be used with classes you would define yourself:

var specialObject : MyClass = new MyClass();

A slight twist on variables is the capability to create true constant values that cannot be changed by

using the

const

keyword:

const age = 32;

This code defines the variable

age

as a constant and assigns a value of

Functions

Functions also take advantage of this new type declaration by providing types for its arguments and

return value. Consider the following example:

function sum(num1 : Integer, num2 : Integer) : Integer {

return num1 + num2;

}

For compatibility with future ECMAScript implementations, you should avoid

using these words as variable or function names.

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