Conditional Compilations in Internet Explorer | JavaScript: Behavioral Layer
Standards Based Development
Conditional Compilation of JScript/JavaScript in ie
Conditional compilation is a feature in ie (ie4+) that acts as an absolute form of object detection, allow control over the browser in regards to which section(s) to compile, or not to compile, while depending on predefined/user defined conditions.
Just think conditional comments for JScript.
can be activated by calling @cc_on statement, or by using @if or @set statements which are part of the conditional compilation's logic. It's usually best to activate the @cc_on_ initially, because then you can include comment elements in the script to dance the browser compatibility dance.
<script type="text/javascript">
/*@cc_on
document.write("JScript version: " + @_jscript_version + ".<br>");
/*@if (@_jscript_version >= 5)
document.write("JScript Version 5.0 or better.<br \/>");
document.write("This text is only seen by browsers that support JScript 5+<br>");
@else @*/
document.write("This text is seen by all other browsers (ie: Firefox, IE 4.x etc)<br>");
/*@end
@*/
</script>
@if@elif@else@end
if else Logic - ie JScript
The script below is only rendered by Trident, supplying different messages for operating systems that are or are not 32 bit:
if else Logic II - Other Browser Inclusive
The conditional compilation below manipulates a parsing error in the common tag purposefully, so that the else is rendered by non-ie browsers, as well as 32&:45bit versions of ie:
if, elseif, else Logic - ie JScript
/*@cc_on
@if (@_jscript_version >= 5)
document.write("IE Browser that supports JScript 5+");
@elif (@_jscript_version >= 4)
document.write("IE Browser that supports JScript 4+");
@else
document.write("Very old IE Browser");
@end
@*/
if, elseif, else logic - Browsers Inclusive
/*@cc_on
/*@if (@_jscript_version >= 5)
document.write("IE Browser that supports JScript 5+");
@elif (@_jscript_version >= 4)
document.write("IE Browser that supports JScript 4+");
@else @*/
document.write("Non IE Browser (one that doesn't support JScript)");
/*@end
@*/
As in the previous browser inclusive conditional compilation example, the last else statement above is also picked up by non-ie browsers.