javascript - 选择标签/选项标签问题

Question

因此，大约一个小时后，无法找到关于如何使用这些标签及其 id、名称和值来实现小数金额以完成对我的表单求和的良好教程。简而言之，我有一个选择框，希望它返回我的选项值和该选项值的金额。

这是 HTML

<tr>
        <th colspan="4" class="label">Shipping Method:
          <select name="shipMethod" id="shipMethod" size="1">
            <option value="">Choose a shipping method</option>
            <option value="priority2">Priority mail $3.20 (4 items or less)</option>
            <option value="priority3">Priority mail $4.30 (6 items or less)</option>
            <option value="priority4">Priority mail $5.40 (8 items or less)</option>
            <option value="overnight">Express $15.75 (4 items or less only)</option>
            <option value="UPS">UPS - 2 day $15.00 (9 - 49 items)</option>
            <option value="free">Free shipping (50+ items only)</option>
          </select>
        </th>
        <td><input name="shippingChg" id="shippingChg" type="text" size="10" maxlength="60" value="" /></td>
      </tr>
      <tr>

我的第一个问题可能是为小数点设置一个循环。这就是我尝试为一个选择框编写循环和函数的方式

 function ship_some_stuff()
 var ship_me= document.getElementById("shipMethod").value; (unsure if this returns
 the option value though, but the idea is to save to a variable later)

 if ship_me == priority2 {
 var shipthisway = 3.20;
 document.getElementById("shippingCHg").value = varshipthisway ;
 }

 if ship_me == priority3{
 var shipthisway = 4.30;
 document.getElementById("shippingCHg").value = varshipthisway ;
 }


 else varship == ""; {
 alert("You haven't selected a shipping Method");
 }

感谢您的帮助!

Answer 1

function get_shipping_charge() { 
  var ship_me= document.getElementById("shipMethod").value;
  if (ship_me == "priority2") return 3.20;
  else if (ship_me == "priority3") return 4.30;
  else return NaN;
}
function do_shipping_charge() {
  var shipthisway = get_shipping_charge();
  if (shipthisway) document.getElementById("shippingCHg").value = shipthisway;
  else alert("You haven't selected a shipping Method");
}