在提交表单之前获取表单的选择列表值

Question

I want to get the values from selected “select list option fields” in a form, before submit the form, and use them as variables in my web page.

For example: I have the form bellow:

<form>
<select name="test">
<option value="111">Something</option>
<option value="222">Something</option>
<option value="333">Something</option>
</select>
</form>

I want to know if my web page user has selected the 111 or the 222 or the 333 value and after that to do something like that:

<%
If user selected the value "111" then 
Do something...
Else
Do something else...
End If
%>

Is there any possible way to do something like that before form's submission?

After a long search I did, I learned that what I need can be done with JavaScript, but unfortunately I am completely ignorant with JavaScript. Could anyone guides me?

Answer 1

You can't use form values as ASP variables without submitting them to the server because ASP runs on the server to do all it's stuff. JavaScript will run in the browser so can perform functions such as calculations without submitting the form to the server.

If you simply want to display the selected form options on the page then us can use JavaScript (or jQuery if you have that running on the page). eg

<script>
 function showValue(s) {
  document.getElementById('myid').innerHTML = s;
 }
</script>
 <form>
<select name="test" onChange="showValue(this.value);">
<option value="111">Something 111</option>
<option value="222">Something 222</option>
<option value="333">Something 333</option>
</select>
</form>
<div id="myid"></div>

If you want to process the selection in some way before submitting the form to either set another form field, or display some calculation you need to either write the calculation function in JavaScript or use AJAX (as suggested by ThatGuyInIT) to get another ASP page to do the processing for you and bring the results back to your page.