替换标签
  var str = "<p><span style='color:#ccc;'>这是测试标签</span><span>这是测试html内容</span></p>";
    nohtml = str.replace(/<span.*?>|<\/span>/ig, "");
 

替换标签和内容

var str = "<p><span style='color:#ccc;'>这是测试标签</span><span>这是测试html内容</span></p>";
    nohtml = str.replace(/<span\s*[^>]*>(.*?)<\/span>/ig, "");