Check duplicate data using Javascript

Use the below Javascript to identify duplicate data - In this sample code, when user enters order number in the tabular form, an error will be thrown if the order number already exists.

<!--duplicate checking for order no -->
<script>
function check_order_no(pThis)
{
var j_item_id=pThis.id;
var k_item_id='#f02'+j_item_id.substr(3);
//alert(j_item_id);
//alert(k_item_id);
var h='#'+j_item_id;
//alert(h);
var a= $(h).val();
var g=$(k_item_id).val();
//alert(a);
//alert(g);

if (g)
{
var get = new htmldb_Get(null, $v('pFlowId'),'APPLICATION_PROCESS=Duplicate_Order_no_check',$v('pFlowStepId'));
get.add('AI_ORDER_NO',a);
//get.add('AI_SHIPPING_ID',g);
ret = get.get();
//alert(ret);
if (ret != 0)
{
var get = new htmldb_Get(null, $v('pFlowId'),'APPLICATION_PROCESS=Duplicate_Order_no_shipping_id',$v('pFlowStepId'));
get.add('AI_ORDER_NO',a);
ret = get.get();
if(ret != g)
{
alert('The Order No is already present.Kindly select another Order No');
$(h).val(null);
$(h).focus();
}
}
}
else
{
var i = 1;
var j=0;
var b,a,c,f;
while (i != 0) {
b = "000" + i;
b = pad(i, 4);
d = $('#f03_'+b).val();
//alert(typeof d);
if (typeof d === "undefined") {
i=0;
}
else
{
if(a == d)
{j= j+1;
}
if(j>1)
{
alert('The Order No is already present.Kindly select another Order No');
$(h).val(null);
$(h).focus();
break;
}
i= i+1;
}
}
}
}
</script>