請問如何使append只出現一次的方法
System Setting是原本存在的,點擊出現Top2路徑後,在點擊不會重複

Top2的div
1.這是主頁面
<html>
<head>
    <title></title>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
    <script type="text/javascript" src="./js/jquery.min.js"></script>
    <script type="text/javascript" src="./js/GlobalVariable.js"></script>
	<script type="text/javascript" src="./js/LoadCSS.js"></script>
    <script type="text/javascript" src="./js/LoadJavascript.js"></script>
    <script type="text/javascript">
        function LoadSystemList()
	{
		$("#Main_Left-List").load("./html/Left-List/SystemSetting.html"); 
		
	}
	function loadpath()
	{
		$("#Main_Top-Path").load("./html/System-Setting/Top1.html"); 
		
	}
	
		function LoadNavigation()
	{
		$("#head-nav").load("./html/Navigation/Navigation.html"); 
		
	}
	
    </script>
</head>
<body style="overflow:auto">
<p>
  <input type="button" name="button" id="button" value="LoadSystemList" onClick="LoadSystemList()">
  <input type="button" name="button" id="button" value="Loadpath" onClick="loadpath()">
  <input type="button" name="button" id="button" value="LoadNavigation" onClick="LoadNavigation()">
</p>
<div id="Main_Base">
	<div id="Main_Top-Logo">
		<div><img src="./image/logo.png"></div>
    </div>
	
<div id="neck">
    <div id="Navigation">
      <ul id="head-nav"></ul>
    </div>
    <div id="Main_Top-Path"></div>
	
</div>
    <div id="Main_Left-List"></div>
    <div id="Main_Center-Content"></div>
    <div id="Main_Bottom-Information"></div>
</div>
</body>
</html>
 
2.這是點list的動作
function main_List2_click(that)
{
	var list = new List1("/html/Top-Path/Top2.html");
	list.AddTopButton();
	list = null;
	var css = new ListCSS(that);
	css.ClickCSS();
	css = null;
}
3.這是append的
List1.prototype.AddTopButton = function()
{
    var html;
	html = this.GetHtml();
	$("#Main_Top-Path").append(html);
	/*
	if(html && html.length>1)
   {
     return 0;
   }
     else
   {
    $("#Main_Top-Path").append(html);
    }*/
};
List1.prototype.GetHtml = function()
{
	var Data;
	var Url = List1.prototype.HtmlPath;
	$.ajax
	({
		url: Url,
		data: "",
		type:"GET",
		dataType:'html',
		async: false,
		cache:false,
		success: function(msg)
		{
			Data = msg;
		},
		error:function(xhr, ajaxOptions, thrownError)
		{
		}
	});
	return Data;
}
4.head檔
function List1(HtmlPath)
{
  List1.prototype.HtmlPath = HtmlPath;
  this.AddTopButton = function(){List1.prototype.AddTopButton()};
}
你可以試試看
List1.prototype.AddTopButton = function()
{
    var html;
    $("#Main_Top-Path").empty();
	html = this.GetHtml();
	$("#Main_Top-Path").append(html);
	/*
	if(html && html.length>1)
   {
     return 0;
   }
     else
   {
    $("#Main_Top-Path").append(html);
    }*/
};
這個方法似乎會把load進來的預設的path蓋掉
	function loadpath()
	{
		$("#Main_Top-Path").load("./html/System-Setting/Top1.html"); 
		
	}
Top1內容
<a href="#"><div style="display:inline-block;text-decoration:none; color:black" onclick="test(this)" onmouseover="main_xxx_mouseover(this)" onmouseout="main_xxx_mouseout(this)">System Setting >></div></a>