JSFiddle - React, Tailwind, and code Playground
HTML
<?php echo form_open('admin/index','class="form-inline"'); ?>
<input id='admin_auto_search' type="text" class="span3" placeholder="Search..">
<select class="span2" name="search_column" id="search_column">
<option value="username">Username</option>
<option value="id">Table ID</option>
<option value="request_id" >Request Id</option>
<option value="created_on">Created On</option>
<option value="first_name">First Name</option>
<option value="last_name">Last Name</option>
<option value="domain_name">Domain Name</option>
<option value="company">Company</option>
<option value="status">Status</option>
<option value="timezone">Time Zone</option>
<option value="plan">Plan</option>
<option value="image">Button Image</option>
</select>
<input type="submit" class="btn btn-primary" value="Search" />
<?php echo form_close();?>
JavaScript
$(function(){
var url="<?php echo base_url('index.php/admin/home/auto_complete');?>";
var column=$('#search_column').val();
$('#search_column').change(function(){
column= $(this).val();
});
$("#admin_auto_search").autocomplete({
source: url+"?search_column="+column
});
});