您应该首先检查localStorage中是否已经存在某些东西:

You should first check if something already exists in the localStorage:

if (localStorage.getItem("todolist") != null) {
    $('#todoList').html(localStorage.getItem("todolist")); // This reads items in our local storage
}

检查此更新:
http://jsbin.com/damedomepi/1/edit?html,js，输出

Check this update:
http://jsbin.com/damedomepi/1/edit?html,js,output