//點擊結帳按鈕

<input class="input" type="button" name="pay" value="結帳" onClick="goto(this)"><br>

//javascript funtion進行判斷

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';
}