[jQuery] Trigger button click event when lost focus in textbox

[ian]

I have a textbox and button to check items in the database. The thing
is I want to trigger the button click event when textbox is lost
focus. This is my click event.

$(document).ready(function() {
        $("#button_from").click(function() {
                $("#waitingFrom").show();
                $.ajax({
                        type: 'POST',
                        url: 'index.php?m=item&a=getPartName',
                        dataType: 'json',
                        data: {
                                part_no: $("#from_part_no").val()
                        },
                        success: function(data) {
                                $("#waitingFrom").hide();
                                
$("#tfrom_part_name").val($("#from_part_name").val
(data.DESCRIPTION).val());
                                $("#tfrom_status").val($("#from_status").val
(data.INVENTORY_ITEM_STATUS_CODE).val());
                                
$("#tfrom_inventory").val($("#from_inventory").val
(data.TRANSACTION_QUANTITY).val());
                                
$("#tfrom_usage_rate").val($("#from_usage_rate").val
(data.USAGE_RATE).val());
                        }
                });
        });

I need help to call that click event when let's say $("#from_part_no")
has lost focus. Thanks in advance.