HTML
<form method="post" name="f1" action='dd-check.php'>
<select class="text" id="course_id" name='course_id' onChange="reload(this.form)">
<option value=''>Select one</option>
<option value=''><?php ?></option>
</select>
<select name="batch_id" id="batch_id">
<option value=''>Select one</option>
<option value=''><?php ?></option>
</select>
</form>
Javascript
<script type="text/javascript">
function reload(form)
{
var val = form.course_id.options[form.course_id.options.selectedIndex].value;
self.location='dd.php?course_id=' + val ;
}
</script>
In here the function reload the form. I want to reload only the first select box data, how to do that?
onchange() event depends on its element, thus reload() does not adjust the second select element "batch_id"
Additionally, before changing the location, add parameter selected index of two option elements.
var s1 = document.getElementById("course_id");
var o1 = s1.options.selectedIndex;
var s2 = document.getElementById("batch_id");
var o2 = s2.options.selectedIndex;
And then, in onload function you restore the option values selected before.
var s1 = document.getElementById("course_id");
s1.options.selectedIndex = o1;
var s2 = document.getElementById("batch_id");
s2.options.selectedIndex = o2;
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