browser/libs/dom.js
function _removeClass( element, cName ){  
    if (!element) return;
    if (typeof element.className === 'string') {
      if( _hasClass( element,cName ) ){  
        element.className = element.className.replace( new RegExp( "(\\s|^)" + cName + "(\\s|$)" )," " ); // replace方法是替换 
        // trim.
        element.className = stringUtils.trim(element.className);
      };  
    }
  }
function _removeClass( element, cName ){  
    if (!element) return;
    if (typeof element.className === 'string') {
      if( _hasClass( element,cName ) ){  
        element.className = element.className.replace( new RegExp( "(\\s|^)" + cName + "(\\s|$)" )," " ); // replace方法是替换 
        // trim.
        element.className = stringUtils.trim(element.className);
      };  
    }
  }
removeClass