Javascript: Conditional Comments and Conditional Compilation

Recently came across some cool new features of Javascript that reduced the amount of coding required. For many years, developers have been writing Javascript code to detect the browser type and accordingly fire javascript functions or do a document.write()But now there are more developer-friendly ways of detecting the browser type and handling content.
Conditional Comments: These look like HTML comments, but IE browsers treat them differently.
Another feature of IE is Conditional Compilation. Non-IE browsers would ignore the @cc block

/*@cc_on
/*@if(@_win32)
document.write("OS is 32-bit, browser is IE.");
@else @*/
document.write("Browser is not IE (ie: is Firefox) or Browser is not 32 bit IE.");
/*@end@*/