//點擊修改數量按鈕
<input class="input" type="button" name="update" value="修改數量" onClick="goto(this)">

//javescript 的funtion判斷動作

function goto(button){
    if(button.value == "繼續購買")	
        window.location='./showall.php';	
    else if(button.value == "清空便當袋")
        window.location='./clean_all.php';
    else if(button.value == "修改數量")
        window.location='./update.php';
    else if(button.value == "結帳")
    	window.location='./NsysuStudent_form.php';
}
function showDetail(lunchboxSN)
{
    var url ='./showdetail.php?sn='+lunchboxSN;
    window.open(url,null,"width=410, height=300");
		
}