간단한dom 검색 함수

 1     var regid = /^#([\w-]*)$/,
 2       regClass = /^\.([\w-]*)$/,
 3       regName = /^(div|a|p|ul|li|input|select|document|body|iframe)$/,
 4       regWhite = /\s*/g;
 5 //    
 6  function _B(name, doc) {
 7         var selector, match, result = [];
 8         var doctemp;
 9         if (doc) {
10             doctemp = (typeof doc == "object" && doc.length > 0 && doc[0] && doc[0].nodeType || doc && doc.nodeType) ? doc : _B(doc);
11         } else {
12             doctemp = document;
13         }
14         selector = name && name.replace(regWhite, "");
15         if (selector) {
16             match = regid.exec(selector);
17             if (match && match[1]) {
18                 result = document.getElementById(match[1]);
19             }
20             match = regClass.exec(selector);
21             if (match && match[1]) {
22                 var elems = doctemp.getElementsByTagName("*");
23                 var len = elems && elems.length || 0;
24                 for (var i = 0; i < len; i++) {
25                     var currentelem = elems[i];
26                     var classlist = currentelem.className.split(/\s+/);
27                     var classlen = classlist.length;
28                     for (var j = 0; j < classlen; j++) {
29                         if (classlist[j] == match[1]) {
30                             result.push(currentelem);
31                             break;
32                         }
33                     }
34                 }
35             }
36             match = regName.exec(selector);
37             if (match && match[1]) {
38                 result = doctemp.getElementsByTagName(match[1]);
39             }
40         }
41         return result ? result : null;
42     }