title: How can i refer to a span element in a form?
body: <p>I have a question with SPAN elements in a FORM in javascript.
  I'm studying 'form &amp; validation' w/headfirst js book and 
  there are some examples like below,: </p>
  
  <p>-.html</p>
  
  <pre><code>&lt;form name="orderform" ...&gt;
  ...
  &lt;input id="zipcode" type="text" name="zipcode" onblur="validateZipcode(this, document.getElementById('zipcode_help'));" /&gt;
  &lt;span id="zipcode_help"&gt;&lt;/span&gt;
  ....
  &lt;input type="button" name="submit" onclick="placeOrder(this.form);" /&gt;
  &lt;/form&gt;
  </code></pre>
  
  <p>-.script</p>
  
  <pre><code>function validateZipcode(inputField, helpText) {
  ....
  helpText.innerHTML = "Please enter a number";
  ....
  }
  
  function placeOrder(form) {
  ...
  if (validateZipcode(form["zipcode"], form["zipcode_help"]) {
  form.submit();
  ....
  }
  </code></pre>
  
  <p>and here is my question.(It's not the same as the title I wrote, btw.:/)
  How can a span element, be referred as "form["zipcode_help"] in the function placeOrder?
  I know all form fields can be referred with its "name" property. 
  and I thought a span element can't be like that because it doesn't belong to a form and haven't even got a name property.</p>
  
  <hr>
  
  <p>I now have changed my question slightly.: How " document.getElementById("zipcode_help")" can be equal to "form["zipcode_help"]? The THING which is found by getElementById method is a SPAN, not a FORM FIELD. And, "zipcode_help" in "form[]" is an ID, not a NAME property, so it seems to me that it's even WRONG in grammar!</p>