jQuery命名空间无冲突

var
 2     // Map over jQuery in case of overwrite
 3     _jQuery = window.jQuery,
 4 
 5     // Map over the $ in case of overwrite
 6     _$ = window.$;
 7 
 8 jQuery.noConflict = function( deep ) {
 9     if ( window.$ === jQuery ) {
10         window.$ = _$;
11     }
12 
13     if ( deep && window.jQuery === jQuery ) {
14         window.jQuery = _jQuery;
15     }
16 
17     return jQuery;
18 };