I found a small solution for this….
1. Create a hidden field to store the value of the combobox
2. Use event.args.item.value to change the value of the hidden field.
// trigger the select event.
$("#combobox").on('select', function (event) {
var elem = document.getElementById("mytext");
elem.value = event.args.item.value;
in Body
`<form class=”form” id=”form” target=”form-iframe” method=”post” action=”echo.php” style=”font-size: 13px; font-family: Verdana; width: 650px;”>
<div name=”list” id=”combobox”>
<input name=”productvalue” type=”hidden” id=”mytext”>
<input style=”margin-top: 10px;” type=”submit” value=”Submit” id=”sendButton” />
</form>`
echo.php
<?php
echo "Wrong Data =";
echo $_POST["list"];
echo "<br />";
echo "Value through hidden feild =";
echo $_POST["productvalue"];
?>
hope this will work for someone 