Error in Javascript Comments

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Last week, I was writing code in javascript when I found something that completly blew off my mind. This is what I found

Stupid IE

Yeah, IE thowing error in javascript comment. For some time I didnot believe what I am seeing, but gradually I came to my senses. Like most developers, first thing I did was started cursing IE on twitter, but later reality struct me and that is to find a solution to this mess.

I dig in a lot of wrong places until I found conditional comments in IE. A sample of how the conditional logic works is below


  @if (@_jscript_version == 10)
    document.write("You are using IE10");

  @elif (@_jscript_version == 9)
    document.write("You are using IE9");

  @elif (@_jscript_version == 5.8)
    document.write("You are using IE8");

  @elif (@_jscript_version == 5.7 && window.XMLHttpRequest)
    document.write("You are using IE7");

  @elif (@_jscript_version == 5.6 || (@_jscript_version == 5.7 && !window.XMLHttpRequest))
    document.write("You are using IE6");

  @elif (@_jscript_version == 5.5)
    document.write("You are using IE5.5");

    document.write("You are using IE5 or older");



To fix this all I need to do is to remove the whole comment. This comment is anyways useful for sourcemaps supported browsers which is long way to go for IE.

Anyways this is just a hack for the time being. The sourcemap specs has been updated due to this problem. To know more check the uglifyjs issue on github

Finally all I have to say is God Bless IE Developers