// A number literal
// A string literal
// A regular expression literal
// Evalutes to the boolean true value
// Evaluates to the boolean false value
// Evaluates to the null value
// Evaluates to the "current" object
We learned about
null in Boolean Values and
null and undefined. Unlike the other keywords,
this is not a constant—it evaluates to
different values in different places in the program. The
this keyword is used in object-oriented
programming. Within the body of a method,
this evaluates to the object on which the
method was invoked. See Invocation Expressions, Chapter 8 (especially Method Invocation), and Chapter 9 for
// Evaluates to the value of the variable i.
// Evaluates to the value of the variable sum.
// undefined is a global variable, not a keyword like null.
assumes it is a variable and looks up its value. If no variable with
that name exists, the expression evaluates to the
undefined value. In the strict mode of
ECMAScript 5, however, an attempt to evaluate a nonexistent variable
throws a ReferenceError instead.