layui动态渲染生成左侧3级菜单的方法(根据后台返

<div class="layui-side layui-bg-black" id="admin-side">
  <div class="layui-side-scroll">
  <ul class="layui-nav layui-nav-tree" id="nav" lay-filter="demo"></ul>
  </div>
 </div>

<link rel="stylesheet" href="../layui/css/layui.css" rel="external nofollow" >
<script src="../lib/jquery-1.12.2.js" type="text/javascript" charset="utf-8"></script>
<script src="../layui/layui.js"></script>

<script>
 //监听选中页签添加样式
 layui.config({
 base: '../layui/' //navbar组件js所在目录
 }).use('navbar', function() {
 var navbar = layui.navbar();
 navbar.set({
  elem: '#nav',
  url: "../layui/nav2.json" //数据源地址，我用了本地写的json数据
 });
 navbar.render();
 //狼蚁网站SEO优化的部分不是必须的
 navbar.on('click(demo)', function(data) {
  console.log(data.elem);
  console.log(data.field.title);//标题
  console.log(data.field.icon);//图标
  console.log(data.field.href);//调转地址
  layer.msg(data.field.href);
 });
 
 //给选中的页签添加选中样式（解决刷新失效问题）
 var url = window.location.href.replace("//", "");
 var relUrl = url.substring(url.lastIndexOf("/") + 1);
 //去掉参数部分
 if (relUrl.indexOf("?") != -1) {
  relUrl = relUrl.split("?")[0];
 }
 $("#leftNavbar a").each(function () {
  var that = this;
 if ($(that).attr("href") == relUrl) {
  $(that).parent().addClass("layui-this");
  $(that).parents("li:eq(0)").addClass("layui-nav-itemed");
  var nodes = $(that).parents("li:eq(0)").find("a .layui-nav-more");
  if (nodes.length > 0) {
  nodes.each(function () {
   if ($(this).parents("dd:eq(0)").find("[href='" + relUrl + 
  "']").length > 0) {
   $(this).parent().parent().addClass("layui-nav-itemed");
   }
  });
  }
  }
 });
 
 });
 </script>

/**
 * navbar.js
 * @author 御风 <1945199284@qq.com>
 */
layui.define(['element', 'common'], function (exports) {
 "use strict";
 var $ = layui.jquery,
 layer = parent.layer === undefined ? layui.layer : parent.layer,
 element = layui.element,
 common = layui.common,
 cacheName = 'tb_navbar';
 
 var Navbar = function () {
 /**
  * 默认配置
  */
 this.config = {
  elem: undefined, //容器
  data: undefined, //数据源
  url: undefined, //数据源地址
  type: 'GET', //读取方式
  cached: false, //是否使用缓存
  spreadOne: false //设置是否只展开一个二级菜单
 };
 this.v = '1.0.0';
 };
 //渲染
 Navbar.prototype.render = function () {
 var _that = this;
 var _config = _that.config;
 if (typeof (_config.elem) !== 'string' && typeof (_config.elem) !== 'object') {
  common.throwError('Navbar error: elem参数未定义或设置出错，具体设置格式请参考文档API.');
 }
 var $container;
 if (typeof (_config.elem) === 'string') {
  $container = $('' + _config.elem + '');
 }
 if (typeof (_config.elem) === 'object') {
  $container = _config.elem;
 }
 if ($container.length === 0) {
  common.throwError('Navbar error:找不到elem参数配置的容器，请检查.');
 }
 if (_config.data === undefined && _config.url === undefined) {
  common.throwError('Navbar error:请为Navbar配置数据源.')
 }
 if (_config.data !== undefined && typeof (_config.data) === 'object') {
  var html = getHtml(_config.data);
  $container.html(html);
  element.init();
  _that.config.elem = $container;
 } else {
  if (_config.cached) {
  var cacheNavbar = layui.data(cacheName);
  if (cacheNavbar.navbar === undefined) {
   $.ajax({
   type: _config.type,
   url: _config.url,
   async: false, //_config.async,
   dataType: 'json',
   success: function (result, status, xhr) {
    //添加缓存
    layui.data(cacheName, {
    key: 'navbar',
    value: result
    });
    var html = getHtml(result);
    $container.html(html);
    element.init();
   },
   error: function (xhr, status, error) {
    common.msgError('Navbar error:' + error);
   },
   complete: function (xhr, status) {
    _that.config.elem = $container;
   }
   });
  } else {
   var html = getHtml(cacheNavbar.navbar);
   $container.html(html);
   element.init();
   _that.config.elem = $container;
  }
  } else {
  //清空缓存
  layui.data(cacheName, null);
  $.ajax({
   type: _config.type,
   url: _config.url,
   async: false, //_config.async,
   dataType: 'json',
   success: function (result, status, xhr) {
   var html = getHtml(result);
   $container.html(html);
   element.init();
   },
   error: function (xhr, status, error) {
   common.msgError('Navbar error:' + error);
   },
   complete: function (xhr, status) {
   _that.config.elem = $container;
   }
  });
  }
 }
 
 //只展开一个二级菜单
 if (_config.spreadOne) {
  var $ul = $container.children('ul');
  $ul.find('li.layui-nav-item').each(function () {
  $(this).on('click', function () {
   $(this).siblings().removeClass('layui-nav-itemed');
  });
  });
 }
 return _that;
 };
 /**
 * 配置Navbar
 * @param {Object} options
 */
 Navbar.prototype.set = function (options) {
 var that = this;
 that.config.data = undefined;
 $.extend(true, that.config, options);
 return that;
 };
 /**
 * 绑定事件
 * @param {String} events
 * @param {Function} callback
 */
 Navbar.prototype.on = function (events, callback) {
 var that = this;
 var _con = that.config.elem;
 if (typeof (events) !== 'string') {
  common.throwError('Navbar error:事件名配置出错，请参考API文档.');
 }
 var lIndex = events.indexOf('(');
 var eventName = events.substr(0, lIndex);
 var filter = events.substring(lIndex + 1, events.indexOf(')'));
 if (eventName === 'click') {
  if (_con.attr('lay-filter') !== undefined) {
  _con.children('ul').find('li').each(function () {
   var $this = $(this);
   if ($this.find('dl').length > 0) {
   var $dd = $this.find('dd').each(function () {
    $(this).on('click', function () {
    var $a = $(this).children('a');
    var href = $a.data('url');
    var icon = $a.children('i:first').data('icon');
    var title = $a.children('cite').text();
    var data = {
     elem: $a,
     field: {
     href: href,
     icon: icon,
     title: title
     }
    }
    callback(data);
    });
   });
   } else {
   $this.on('click', function () {
    var $a = $this.children('a');
    var href = $a.data('url');
    var icon = $a.children('i:first').data('icon');
    var title = $a.children('cite').text();
    var data = {
    elem: $a,
    field: {
     href: href,
     icon: icon,
     title: title
    }
    }
    callback(data);
   });
   }
  });
  }
 }
 };
 /**
 * 清除缓存
 */
 Navbar.prototype.cleanCached = function () {
 layui.data(cacheName, null);
 };
 /**
 * 获取html字符串
 * @param {Object} data
 */
 function getHtml(data) {
 var ulHtml = '<ul class="layui-nav layui-nav-tree beg-navbar">';
 for (var i = 0; i < data.length; i++) {
  if (data[i].spread) {
  ulHtml += '<li class="layui-nav-item layui-nav-itemed">';
  } else {
  ulHtml += '<li class="layui-nav-item">';
  }
  if (data[i].children !== undefined && data[i].children !== null && data[i].children.length > 0) {
  ulHtml += '<a href="javascript:;" rel="external nofollow" rel="external nofollow" rel="external nofollow" >' + data[i].title;
  ulHtml += '<span class="layui-nav-more"></span>';
  ulHtml += '</a>';
  ulHtml += '<dl class="layui-nav-child">';
  //二级菜单
  for (var j = 0; j < data[i].children.length; j++) {
   //是否有孙子节点
   if (data[i].children[j].children !== undefined && data[i].children[j].children !== null && data[i].children[j].children.length > 0) {
   ulHtml += '<dd>';
   ulHtml += '<a href="javascript:;" rel="external nofollow" rel="external nofollow" rel="external nofollow" >' + data[i].children[j].title;
   ulHtml += '<span class="layui-nav-more"></span>';
   ulHtml += '</a>';
   //三级菜单
   ulHtml += '<dl class="layui-nav-child">';
    var grandsonNodes = data[i].children[j].children;
    for (var k = 0; k < grandsonNodes.length; k++) {
    ulHtml += '<dd>';
    ulHtml += '<a href="'+ grandsonNodes[k].href +'" rel="external nofollow" >' + grandsonNodes[k].title + '</a>';
    ulHtml += '</dd>';
    }
   ulHtml += '</dl>';
   ulHtml += '</dd>';
   }else{
   ulHtml += '<dd>';
   ulHtml += '<a href="'+data[i].children[j].href+'" rel="external nofollow" >' + data[i].children[j].title;
   ulHtml += '</a>';
   ulHtml += '</dd>';
   }
   //ulHtml += '<dd title="' + data[i].children[j].title + '">'; 
  }
  ulHtml += '</dl>';
  } else {
  var dataUrl = (data[i].href !== undefined && data[i].href !== '') ? 'data-url="' + data[i].href + '"' : '';
  //ulHtml += '<a href="javascript:;" rel="external nofollow" rel="external nofollow" rel="external nofollow" ' + dataUrl + '>';
  ulHtml += '<a href="' + data[i].href + '" rel="external nofollow" ' + dataUrl + '>';
  if (data[i].icon !== undefined && data[i].icon !== '') {
   if (data[i].icon.indexOf('fa-') !== -1) {
   ulHtml += '<i class="fa ' + data[i].icon + '" aria-hidden="true" data-icon="' + data[i].icon + '"></i>';
   } else {
   ulHtml += '<i class="layui-icon" data-icon="' + data[i].icon + '">' + data[i].icon + '</i>';
   }
  }
  ulHtml += '<cite>' + data[i].title + '</cite>';
  ulHtml += '</a>';
  }
  ulHtml += '</li>';
 }
 ulHtml += '</ul>';
 
 return ulHtml;
 }
 
 var navbar = new Navbar();
 
 exports('navbar', function (options) {
 return navbar.set(options);
 });
});

/**
 * common.js
 * @author 御风 <1945199284@qq.com>
 */
layui.define(['layer'], function(exports) {
 "use strict";
 
 var $ = layui.jquery,
 layer = layui.layer;
 
 var common = {
 /**
  * 抛出一个异常错误信息
  * @param {String} msg
  */
 throwError: function(msg) {
  throw new Error(msg);
  return;
 },
 /**
  * 弹出一个错误提示
  * @param {String} msg
  */
 msgError: function(msg) {
  layer.msg(msg, {
  icon: 5
  });
  return;
 }
 };
 
 exports('common', common);
});

[
 {
 "title": "首页",
 "icon": " ",
 "spread": true,
 "href": ""
 },
 {
 "title": "一级导航",
 "icon": "fa-stop-circle",
 "spread": true,
 "href": "http://www.baidu.com",
 "children": [
 {
 "title": "二级导航",
 "icon": "",
 "href": "lala.html",
 "spread": true,
 "children": [
  {
  "title": "三级导航",
  "icon": " ",
  "href": "button.html"
  },
  {
  "title": "三级导航",
  "icon": " ",
  "href": "buttwswon.html"
  }
 ]
 }
 ]
 },
 {
 "title": "一级导航",
 "icon": "fa-stop-circle",
 "spread": true,
 "href": "http://www.baidu.com"
 
 },
 {
 "title": "一级导航",
 "icon": "fa-stop-circle",
 "spread": true,
 "href": "http://www.baidu.com"
 
 },
 {
 "title": "一级导航",
 "icon": "fa-stop-circle",
 "spread": true,
 "href": "http://www.baidu.com"
 
 }
]