YUI Compressor: Doesn't like IE Detection (cc_on)

[marczych]

I'm having problems compressing filedrop.js using YUI Compressor:

[I]> java -jar yuicompressor-2.4.8.jar --type js --charset utf-8 filedrop.js
[ERROR] in filedrop.js
  568:66:missing } after property list
[ERROR] in filedrop.js
  569:11:syntax error
[ERROR] in filedrop.js
  573:14:syntax error
[ERROR] in filedrop.js
  577:12:syntax error
[ERROR] in filedrop.js
  578:4:syntax error
[ERROR] in filedrop.js
  603:10:syntax error
[ERROR] in filedrop.js
  1385:9:missing ) after argument list
[ERROR] in filedrop.js
  1385:10:syntax error
[ERROR] in filedrop.js
  1579:3:syntax error
[ERROR] in filedrop.js
  1590:10:syntax error
[ERROR] in filedrop.js
  1831:3:syntax error
[ERROR] in filedrop.js
  1834:10:syntax error
[ERROR] in filedrop.js
  1835:10:syntax error
[ERROR] in filedrop.js
  1849:10:syntax error
[ERROR] in filedrop.js
  2375:3:syntax error
[ERROR] in filedrop.js
  2385:10:syntax error
[ERROR] in filedrop.js
  2389:11:invalid return
[ERROR] in filedrop.js
  2390:3:syntax error
[ERROR] in filedrop.js
  2466:10:syntax error
[ERROR] in filedrop.js
  2467:8:syntax error
[ERROR] in filedrop.js
  2468:13:missing ; before statement
[ERROR] in filedrop.js
  2470:7:syntax error
[ERROR] in filedrop.js
  2471:44:missing ; before statement
[ERROR] in filedrop.js
  2476:7:syntax error
[ERROR] in filedrop.js
  2489:19:invalid return
[ERROR] in filedrop.js
  2491:19:invalid return
[ERROR] in filedrop.js
  2506:17:invalid return
[ERROR] in filedrop.js
  2515:13:invalid return
[ERROR] in filedrop.js
  2516:5:syntax error
[ERROR] in filedrop.js
  2521:1:syntax error
[ERROR] in filedrop.js
  1:0:Compilation produced 30 syntax errors.
org.mozilla.javascript.EvaluatorException: Compilation produced 30 syntax errors.
    at com.yahoo.platform.yui.compressor.YUICompressor$1.runtimeError(YUICompressor.java:172)
    at org.mozilla.javascript.Parser.parse(Parser.java:396)
    at org.mozilla.javascript.Parser.parse(Parser.java:340)
    at com.yahoo.platform.yui.compressor.JavaScriptCompressor.parse(JavaScriptCompressor.java:315)
    at com.yahoo.platform.yui.compressor.JavaScriptCompressor.<init>(JavaScriptCompressor.java:536)
    at com.yahoo.platform.yui.compressor.YUICompressor.main(YUICompressor.java:147)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at com.yahoo.platform.yui.compressor.Bootstrap.main(Bootstrap.java:21)

It fails on these lines:

    isIE6: /*@cc_on/*@if(@_jscript_version<=5.7)true@else@*/false/*@end@*/,
    isIE9: /*@cc_on/*@if(@_jscript_version<=9)true@else@*/false/*@end@*/,

I commented on an existing YUI Compressor issue but I don't expect them to do anything about it soon: yui/yuicompressor#119 (comment)

Is there any workaround for this? Perhaps another method of IE detection?

[marczych]

My workaround was just to use UserAgent sniffing rather than conditional compilation which can be found at iFixit#1. Feel free to cherry-pick the commit in this repo if you'd like.