fix: 修复 nav 在 IE 中的兼容性问题 (#2415)

* fix(nav): 导航菜单在 IE 中的兼容性问题

* treeTable(test): 添加 IE 测试

examples/treeTable.html

@@ -26,6 +26,53 @@
 
 <script src="../src/layui.js"></script>
 <script>
+// IE8 support
+// ES5 15.4.4.19 Array.prototype.map ( callbackfn [ , thisArg ] )
+// From https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Array/Map
+if (!Array.prototype.map) {
+  Array.prototype.map = function (fun /*, thisp */) {
+    if (this === void 0 || this === null) { throw TypeError(); }
+
+    var t = Object(this);
+    var len = t.length >>> 0;
+    if (typeof fun !== "function") { throw TypeError(); }
+
+    var res = []; res.length = len;
+    var thisp = arguments[1], i;
+    for (i = 0; i < len; i++) {
+      if (i in t) {
+        res[i] = fun.call(thisp, t[i], i, t);
+      }
+    }
+
+    return res;
+  };
+}
+
+// ES5 15.4.4.20 Array.prototype.filter ( callbackfn [ , thisArg ] )
+// From https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Array/Filter
+if (!Array.prototype.filter) {
+  Array.prototype.filter = function (fun /*, thisp */) {
+    if (this === void 0 || this === null) { throw TypeError(); }
+
+    var t = Object(this);
+    var len = t.length >>> 0;
+    if (typeof fun !== "function") { throw TypeError(); }
+
+    var res = [];
+    var thisp = arguments[1], i;
+    for (i = 0; i < len; i++) {
+      if (i in t) {
+        var val = t[i]; // in case fun mutates this
+        if (fun.call(thisp, val, i, t)) {
+          res.push(val);
+        }
+      }
+    }
+
+    return res;
+  };
+}
 layui.use(['treeTable', 'dropdown', 'layer'], function(){
   var treeTable = layui.treeTable;
   var dropdown = layui.dropdown;

src/modules/element.js

@@ -519,8 +519,8 @@ layui.define('jquery', function(exports){
           var itemElem = othis.find('.'+NAV_ITEM);
           
           // hover 滑动效果
-          var hasBarElem = othis.find('.'+NAV_BAR)[0];
-          if (hasBarElem) hasBarElem.remove();
+          var hasBarElem = othis.find('.'+NAV_BAR);
+          if (hasBarElem[0]) hasBarElem.remove();
           othis.append(bar);
           ( othis.hasClass(NAV_TREE)
             ? itemElem.find('dd,>.'+ NAV_TITLE)