/**
 * 格式化xml
 * @param content
 * @returns {*}
 */
this.parse_xml = function(content) {
  let xml_doc = null;
  try {
    xml_doc = (new DOMParser()).parseFromString(content.replace(/[\n\r]/g, ""), 'text/xml');
  } catch (e) {
    return false;
  }

  function build_xml(index, list, element) {
    let t = [];
    for (let i = 0; i < index; i++) {
      t.push('&nbsp;&nbsp;&nbsp;&nbsp;');
    }
    t = t.join("");
    list.push(t + '&lt;<span class="code-key">'+ element.nodeName +'</span>&gt;\n');
    for (let i = 0; i < element.childNodes.length; i++) {
      let nodeName = element.childNodes[i].nodeName;
      if (element.childNodes[i].childNodes.length === 1) {
        let value = element.childNodes[i].childNodes[0].nodeValue;
        let value_color = !isNaN(Number(value)) "'+ value_color +'">' + value + '</span>';
        let item = t + '&nbsp;&nbsp;&nbsp;&nbsp;&lt;<span class="code-key">' + nodeName +
          '</span>&gt;' + value_txt + '&lt;/<span class="code-key">' + nodeName + '</span>&gt;\n';
        list.push(item);
      } else {
        build_xml(++index, list, element.childNodes[i]);
      }
    }
    list.push(t + '&lt;/<span class="code-key">'+ element.nodeName +'</span>&gt;\n');
  }
  let list = [];
  build_xml(0, list, xml_doc.documentElement);
  return list.join("");
};

.code-string{color:#993300;}
.code-number{color:#cc00cc;}
.code-boolean{color:#000033;}
.code-null{color:magenta;}
.code-key{color:#003377;font-weight:bold;}