WEB前端开发
专注前端开发，关注用户体验

从一个js文件中分离出来的，还不知道作者是谁。

在指定的DOM节点context下按CSS2,CSS3选择器的定义去找出相关的DOM节点
支持的选择器：
E[att^="val"],E[att$="val"],E[att*="val"],E[att~="val"],E[att|="val"],E[att!="val"],E[att="val"]
E:enabled,E:disabled,E:checked,E:not(s)
+ E.class
> E.class
E.class
E#id
E
参数：pattern：CSS2 Selector可以通过逗号分隔多个选择器,context指定要查找的DOM节点范围
返回值：[DOM Collection]

function selector(pattern, context) {
 var re = new RegExp('([a-z]*)([\.#:]*)(.*|$)', 'ig');
 var match = re.exec(pattern);
 //alert(context);
 var conditions = []; 
 if (match[2] == '#') conditions.push(['id', match[3]]);
 else if(match[2] == '.') conditions.push(['className', match[3]]);
 else if(match[2] == ':') conditions.push(['type', match[3]]); 
 var s = match[3].replace(/\[(.*)\]/g,'$1').split(<a href="mailto:'@'">'@'</a>);
 for(var i=0; i<s.length; i++) {
  var cc = null;
  if (cc = /([\w]+)([=^%!$~]+)(.*)$/.exec(s[i])){
   conditions.push([cc[1], cc[2], cc[3]]);
  }
 }
 var list = (context || document).getElementsByTagName(match[1] || "*"); 
 if(conditions) {
  var elements = [];
  var attrMapping = {'for': 'htmlFor', 'class': 'className'};
  for(var i=0; i<list.length; i++) {
   var pass = true;
   for(var j=0; j<conditions.length; j++) {
    var attr = attrMapping[conditions[j][0]] || conditions[j][0];
    var val = list[i][attr] || (list[i].getAttribute ? list[i].getAttribute(attr) : '');
    var pattern = null;
    if(conditions[j][1] == '=') {
     pattern = new RegExp('^'+conditions[j][2]+'$', 'i');
    } else if(conditions[j][1] == '^=') {
     pattern = new RegExp('^' + conditions[j][2], 'i');
    } else if(conditions[j][1] == '$=') {
     pattern = new RegExp(conditions[j][2] + '$', 'i');
    } else if(conditions[j][1] == '%=') {
     pattern = new RegExp(conditions[j][2], 'i');
    } else if(conditions[j][1] == '~=') {
     pattern = new RegExp('(^|[ ])' + conditions[j][2] + '([ ]|$)', 'i');
    }
    if(pattern && !pattern.test(val)) {
     pass = false;
     break;
    }
   }
   if(pass) elements.push(list[i]);
  }
  return elements;
 } else {
  return list;
 }
}