关于YUI压缩器和JavaScript

Question

I am using handlebars in my website. So that I need to send the 'handlebars.runtime.js' to the client side. However I found that the 'handlebars.runtime.js' from the offocial website isn't compressed, so I use the YUI compressor to compress it.

Something weird occurred when I checked the compressed 'handlebars.runtime.js': some codes are disappeared in the compressed one when I compared to the previous one. And the very beginning of the compressed one is like this:

/*!

 handlebars v1.3.0

 Copyright (C) 2011 by Yehuda Katz

 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal
 in the Software without restriction, including without limitation the rights
 to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 copies of the Software, and to permit persons to whom the Software is
 furnished to do so, subject to the following conditions:

 The above copyright notice and this permission notice shall be included in
 all copies or substantial portions of the Software.

 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 THE SOFTWARE.

 @license
 */
;var Handlebars=(function(){v (rest of the codes...)

As you can see, the comments are not deleted by the YUI compressor and there is a weird semicolon at the very beginning of the codes. Can anyone explain this? Thanks!

PS: the beginning uncompressed 'handlebars.runtime.js' is like this:

/*!

handlebars v1.3.0

Copyright (C) 2011 by Yehuda Katz

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.

@license
*/
/* exported Handlebars */
var Handlebars = (function() {
// handlebars/safe-string.js
var __module3__ = (function() {
"use strict";
var __exports__;
// Build out our basic SafeString type
function SafeString(string) {
this.string = string;
}

 SafeString.prototype.toString = function() {
  return "" + this.string;
 };

  __exports__ = SafeString;
  return __exports__;
})();

Answer 1

It's still present because of the exclamation mark in the starting comment /*!

This is intended, as usually when using open source library, you want to preserve the copyright notes