如何使用 HTML 中的下拉列表更改元素

我目前正在为黑莓10开发eBay应用程序，遇到了一个问题。问题是，我想要一个下拉菜单（以便用户可以选择他们想要访问的 eBay 国家/地区），但我不知道如何在屏幕底部获得一个按钮以转到正确的页面在下拉列表中选择了选项。

http://i1078.photobucket.com/albums/w483/tobster619/Blackberry%2010/help_zps923bcc21.png

这是代码的分解版本，可以在附图中看到：

<script type="text/javascript"> 
//verify the welcome screen 
function verifywelcome(){ 
if (document.getElementById('checkbox').get... == true) { 
alert('checkbox is checked'); 
//set the localstorage item 
localStorage.welcome = "true" ; 
} else if (document.getElementById('checkbox').get... == false) { 
alert('checkbox is not checked'); 
//set the localstorage item 
localStorage.welcome = "false"; 
} 
} 
//if you want to remove the localStorage key to redisplay the welcome screen again.    use: localStorage.removeItem('welcome'); 
function welcome() { 
//check if welcome exists, if not: create it 
if (localStorage.welcome == null) { localStorage.welcome = "true" }; 
if (localStorage.getItem('welcome') == "true") /* if it is true: */ { 
bb.pushScreen('welcome.html', 'welcome'); 
} 
else if (localStorage.getItem('welcome') == "false") { 
bb.pushScreen('menu.html', 'menu'); 
} 
} 
//verify the welcome screen 
function verifywelcome2(){ 
if (document.getElementById('checkbox').get... == true) { 
alert('checkbox is checked'); 
//set the localstorage item 
localStorage.welcome = "true" ; 
} else if (document.getElementById('checkbox').get... == false) { 
alert('checkbox is not checked'); 
//set the localstorage item 
localStorage.welcome = "false"; 
} 
} 

//if you want to remove the localStorage key to redisplay the welcome screen again. use: localStorage.removeItem('welcome'); 
function welcome() { 
//check if welcome exists, if not: create it 
if (localStorage.welcome == null) { localStorage.welcome = "true" }; 
if (localStorage.getItem('welcome') == "true") /* if it is true: */ { 
bb.pushScreen('welcome.html', 'welcome'); 
} 
else if (localStorage.getItem('welcome') == "false") { 
bb.pushScreen('menu2.html', 'menu2'); 
} 
} 
function onLoadFunctions() { 
// Register the app. Make sure you get a unique UUID! 
blackberry.event.addEventListener('ona... function (accessible, status) { 
if (status === 'unregistered') { 
blackberry.bbm.platform.register({ 
uuid: 'b1e606e8-66e5-41db-a932-6ad42f2aa59c' 
}); 
} else if (status === 'allowed') { 
bbm.registered = accessible; 
} 
}, false) 
} 
</script> 
<select id="countryselector"> 
<option value="eBay UK" selected="true" onchange="verifywelcome();bb.pushScreen(...  'Menu');onLoadFunctions();">eBay UK</option> 
<option value="eBay US" "verifywelcome2();bb.pushScreen('menu2.h... 'Menu2');onLoadFunctions();">eBay US</option> 
<option value="eBay CA">eBay CA</option> 
</select> 
<table> 
<tr> 
<td class="cell" style="margin-top:13px;">Show this page on launch</td> 
<td class="cell" ><input id="checkbox" type="checkbox" checked="true" value="one"/>    </td> 
</tr> 
</table> 
<!--BOTTOM PAGE MENU BAR --> 
<div data-bb-type="action-bar"> 
<div data-bb-type="action" data-bb-style="button" data-bb-img="IMG/ic_next.png"  onclick="verifywelcome();bb.pushScreen('... 'Menu');onLoadFunctions();">The Native eBay Experience Awaits...</div> 
</div>  

因此，当用户单击按钮（我刚刚向您展示的代码的最后一部分）时，它将带他们到eBay UK（menu.html），我的问题是：如果用户选择eBay US （menu2.html），我该如何更改它，当他们单击按钮时，它会将他们带到menu2.html（eBay US）而不是菜单.html（eBay UK），同时仍然允许不同的onclick功能来改变work （"verifywelcome（）;verifywelcome2（）;onLoadFunctions（）;"）？

提前感谢！