code: function getLabelTarget(target){
          var labelDom;
          if(target.nodeName !== 'INPUT'){
              if(target.nodeName === 'LABEL'){
                  labelDom = target;
              }
              else if(target.parentNode.nodeName === 'LABEL'){
                  labelDom = target.parentNode;
              }
          }
          if(labelDom){
              // label标签，替换为目标表单项
              var forValue = labelDom.getAttribute && labelDom.getAttribute('for');
              var labelTargets;
              if(forValue){
                  // 有指定for
                  labelTargets = findDomPathElement('#'+forValue);
                  if(labelTargets.length === 1 && isDomVisible(labelTargets[0])){
                      return labelTargets[0];
                  }
              }
              else{
                  // 没有指定for
                  labelTargets = labelDom.querySelectorAll('input');
                  if(labelTargets.length === 1 && isDomVisible(labelTargets[0])){
                      return labelTargets[0];
                  }
              }
          }
      }
docs: 调整label为for的表单DOM,以增加PATH稳定性