@cc_on Statement (JavaScript)

The @cc_on statement activates conditional compilation within comments in a script.

It is not common to use conditional compilation variables in scripts written for ASP or ASP.NET pages or command-line programs because the capabilities of the compilers can be determined by using other methods.

When you write a script for a Web page, always put conditional compilation code in comments. This enables hosts that do not support conditional compilation to ignore it.

It is strongly recommended that you use the @cc_on statement in a comment, so that browsers that do not support conditional compilation will accept your script as valid syntax:

An @if or @set statement outside of a comment also activates conditional compilation.

The following example illustrates the use of the @cc_on statement.

/*@cc_on @*/
/*@
    document.write("JavaScript version: " + @_jscript_version + ".");
    document.write("<br />");
    @if (@_win32)
        document.write("Running on the 32-bit version of Windows.");
    @elif (@_win16)
        document.write("Running on the 16-bit version of Windows.");
    @else
        document.write("Running on a different operating system.");
    @end
@*/

Supported in all versions of Internet Explorer, but not in Windows Store apps.

Reference

Concepts