<script>
  window.onload = function () { //绑定页面加载完毕时的事件处理函数
    var table = document.getElementByTagName("table")[0]; //获取表格外框的引用
    var del = document.getElementById("del");
    var reset = document.getElementById("reset");
    del.onclick = function () {
      table.removeAttribute("border");
    }
    reset.onclick = function () {
      table.setAttribute("border", "2");
    }
</script>
<table width="100%" border="2">
  <tr>
    <td>数据表格</td>
  <tr>
</table>
<button id="del">删除</button><button id="reset">恢复</button>

<script>
  function hasClass (element, className) { //类名检测函数
    var reg = new RegExp ('(\\s|^)' + className + '(\\s|$)');
    return reg.test (element, className); //使用正则检测是否有相同的样式
  }
  function deleteClass (element, className) {
    if (hasClass (element, className)) {
      element.className.replace (reg, ' '); //捕获要删除样式，然后替换为空白字符串
    }
  }
</script>
<div id="red" class="red blue bold">盒子</div>
<script>
  var red = document.getElementById ("red");
  deleteClass (red, 'blue');
</script>

document.getElementById('riskTypePie').removeAttribute("style");

var node=document.getElementById('chartWrap');
var attr=n.getAttributeNode('style');
node.removeAttributeNode(attr);