Conditional compilation allows the use of new JScript language
features without sacrificing compatibility with older versions
that do not support the features. Conditional compilation is
activated by using the @cc_on statement, or using an @if or @set
statement. Some typical uses for conditional compilation include
using new features in JScript, embedding debugging support into
a script, and tracing code execution. Always place conditional
compilation code in comments, so that hosts (like Netscape
Navigator) that do not understand conditional compilation will
ignore it. Here is an example. /*@cc_on @*/ /*@if
(@_jscript_version >= 4) alert("JScript version 4 or better");
@else @*/ alert("You need a more recent script engine."); /*@end
@*/ This example uses special comment delimiters that are only
used if conditional compilation is activated by the @cc_on
statement. Scripting engines that do not support conditional
compilation only see the message informing of the need for a new
scripting engine.