title: Assign Numerical Value from Drop down for HTML5 form
body: <p>Trying to take my "Room Type" drop down and convert the values to be used in the form oninput formula. However, I'm having no luck finding anywhere that details the structure of a select box.</p>
  
  <pre><code>&lt;form oninput="total.value = (nights.valueAsNumber * rmtp.valueAsNumber) + 
       ((guests.valueAsNumber) * 10)"&gt;
          &lt;TABLE class="Internal Info" align="center"&gt;
      &lt;TR&gt;
      &lt;TD&gt;&lt;label&gt;Full name:&lt;/label&gt;&lt;/TD&gt;
      &lt;TD&gt;&lt;input type="text" id="full_name" name="full_name" placeholder="Jane Doe" required&gt;&lt;/TD&gt;
      &lt;/TR&gt;
      &lt;TR&gt;&lt;TD&gt;
        &lt;label&gt;Email address:&lt;/label&gt;&lt;/TD&gt;
      &lt;TD&gt;  &lt;input type="email" id="email_addr" name="email_addr" required&gt;&lt;/TD&gt;&lt;/TR&gt;
      &lt;TR&gt;
        &lt;TD&gt;&lt;label&gt;Repeat email address:&lt;/label&gt;&lt;/TD&gt;
        &lt;TD&gt;&lt;input type="email" id="email_addr_repeat" name="email_addr_repeat" required 
         oninput="check(this)"&gt;&lt;/TD&gt;
      &lt;/TR&gt;
        &lt;TR&gt;&lt;TD&gt;&lt;label&gt;Arrival date:&lt;/label&gt;&lt;/TD&gt;
      &lt;TD&gt;  &lt;input type="date" id="arrival_dt" name="arrival_dt" required&gt;&lt;/TD&gt;&lt;/TR&gt;
      &lt;TR&gt;
        &lt;TD&gt;&lt;label&gt;Number of nights :&lt;/label&gt;&lt;/TD&gt;
        &lt;TD&gt;&lt;input type="number" id="nights" name="nights" value="1" min="1" max="30" required&gt;&lt;/TD&gt;
      &lt;/TR&gt;
      &lt;TR&gt;
        &lt;TD&gt;&lt;label&gt;Room Type&lt;/label&gt;&lt;/TD&gt;
        &lt;TD&gt;&lt;select name="rmtp" required&gt;
        &lt;option value="80"&gt;Standard($80/N)&lt;/option&gt;
        &lt;option value="90"&gt;Superior($90/N)&lt;/option&gt;
        &lt;option value="110"&gt;Deluxe($110/N)&lt;/option&gt;
        &lt;option value="130"&gt;Family($130/N)&lt;/option&gt;
        &lt;option value="120"&gt;Riviera Suite($120/N)&lt;/option&gt;
        &lt;option value="199"&gt;Honeymoon Package($199/N)&lt;/option&gt;
        &lt;/select&gt;
  
        &lt;/TD&gt;
      &lt;/TR&gt;
        &lt;TR&gt;&lt;TD&gt;&lt;label&gt;Number of additional guests (two guests included at the base price; each additional guest adds $10.00 per night):&lt;/label&gt;&lt;/TD&gt;
        &lt;TD&gt;&lt;input type="number" id="guests" name="guests" value="0" min="0" max="4" required&gt;&lt;/TD&gt;&lt;/TR&gt;
      &lt;TR&gt;
        &lt;TD&gt;&lt;label&gt;Estimated total:&lt;/label&gt;&lt;/TD&gt;
      &lt;TD&gt;  $&lt;output id="total" name="total"&gt;80&lt;/output&gt;.00&lt;/TD&gt;
        &lt;/TR&gt;
        &lt;TR&gt;
        &lt;TD&gt;&lt;label&gt;Promo code:&lt;/label&gt;&lt;/TD&gt;
        &lt;TD&gt;&lt;input type="text" id="promo" name="promo" pattern="[A-Za-z0-9]{6}" 
         title="Promo codes consist of 6 alphanumeric characters."&gt;&lt;/TD&gt;&lt;/TR&gt;&lt;/TABLE&gt;
      &lt;br /&gt;
      &lt;/form&gt;
  
      &lt;script&gt;
      function check(input) {
        if (input.value != document.getElementById('email_addr').value) {
          input.setCustomValidity('The two email addresses must match.');
        } else {
          // input is valid -- reset the error message
          input.setCustomValidity('');
        }
      }
      &lt;/script&gt;
  </code></pre>