diff --git a/LinkedList.js b/LinkedList.js
new file mode 100644
index 0000000..d154b6f
--- /dev/null
+++ b/LinkedList.js
@@ -0,0 +1,69 @@
+function ListNode (id, router, prev, next) {
+    this.id = id;
+    this.router = router;
+    this.prev = prev;
+    this.next = next;
+}
+
+function LinkedList(capacity) {
+    this.head = new ListNode(null, null);
+    this.tail = new ListNode(null, null);
+    this.head.next = this.tail;
+    this.tail.prev = this.head;
+    this.LinkedListMap = {};
+    this.capacity = capacity;
+    this.size = 0;
+}
+
+LinkedList.prototype.push = function (route, id) {
+    let node = this.LinkedListMap[id];
+    if (!node ||  node.next === this.tail){
+        // 正常的push
+        if (this.size === this.capacity) {
+            this._remove(this.head.next);
+        }
+    } else {
+        // 处理当前currentRoute不是最后一个情况下的push，将当前节点后面的路由删除掉
+        node.next = this.tail;
+        this.tail.prev = node;
+    }
+    return this._add(route);
+}
+
+LinkedList.prototype._remove = function (route) {
+    route.prev.next = route.next;
+    route.next.prev = route.prev;
+    delete this.LinkedListMap[route.id];
+    return route;
+}
+
+LinkedList.prototype._add = function (route) {
+    var tail = this.tail;
+    var prev = tail.prev;
+    var node = new ListNode(route.id, route, prev, tail);
+    this.LinkedListMap[route.id] = node;
+    prev.next = node;
+    tail.prev = node;
+    return node;
+}
+
+LinkedList.prototype.remove = function(id) {
+    let route = this.LinkedListMap[id];
+    this._remove(route);
+}
+
+LinkedList.prototype.forward = function (id) {
+    let route = this.LinkedListMap[id];
+    if (route.next && route.next !== this.tail) {
+        return route.next;
+    }
+}
+
+LinkedList.prototype.back = function (id) {
+    let route = this.LinkedListMap[id];
+    if (route.prev && route.prev !== this.head) {
+        return route.prev.router;
+    }
+}
+  
+module.exports = LinkedList;
\ No newline at end of file
diff --git a/router.js b/router.js
index d8926ea..664bb06 100644
--- a/router.js
+++ b/router.js
@@ -1,27 +1,55 @@
+const LinkedList = require('./LinkedList');
+
 function Router(routes, defaultRoute) {
   //TODO
+  this._ROUTE_MAP = {};
+  routes.forEach((item) => {
+    var pageId = item.id;
+    if (pageId) {
+      this._ROUTE_MAP[pageId] = item;
+    }
+  });
+
+  // 通过带索引的链表模拟history，不用关心数组的下标和来回切换上下的访问
+  this.routerHistory = new LinkedList(5);
+  if (defaultRoute) {
+    this.push(defaultRoute);
+  }
 }
 
 //初始化，可多次初始化
 Router.prototype.init = function(routes, defaultRoute) {
   //TODO
-  this.currentRoute
-  this.oldRoute
 }
 
 //切换路由
 Router.prototype.push = function(route, callback) {
   //TODO
+  if (this._ROUTE_MAP[route]) {
+    this.routerHistory.push(this._ROUTE_MAP[route], this.currentRoute && this.currentRoute.id, );
+    this._enter(route)
+    return callback && callback();
+  }
+}
+
+Router.prototype._enter = function(route) {
+  var router = this._ROUTE_MAP[route];
+  this.currentRoute = router;
+  if (router.handler) {
+    router.handler();
+  }
 }
 
 //前进
 Router.prototype.forward = function () {
-  history.forward();
+  var forward = this.routerHistory.forward(this.currentRoute.id);
+  this.currentRoute = forward;
 }
 
 //后退
 Router.prototype.back = function () {
-  history.back();
+  var back = this.routerHistory.back(this.currentRoute.id);
+  this.currentRoute = back;
 }
 
 //切换页面：route为字符串，为空则隐藏所有路由
@@ -29,4 +57,11 @@ Router.prototype.changePage = function(route) {
   //TODO
 }
 
-module.exports = Router
\ No newline at end of file
+Router.prototype.replace = function (id) {
+  let route = this._ROUTE_MAP[id];
+  this.routerHistory.remove(this.currentRoute.id);
+  this.routerHistory.push(route);
+  this.currentRoute = route;
+}
+
+module.exports = Router;
\ No newline at end of file
diff --git a/test/index.spec.js b/test/index.spec.js
index 27b7c39..1099f87 100644
--- a/test/index.spec.js
+++ b/test/index.spec.js
@@ -1,3 +1,4 @@
+const Router = require('../router.js');
 describe('初始化路由', () => {
   it('default route', () => {
     //路由表