How to add simple jquery loader/spinner using ajax?

Question

I just need a little help here about adding a simple loader/spinner in my form. I have a search form in my jquery. I want to include a loader/spinner image while the search is on process. After the process is done the loader will be not visible again.

Here's my code, by the way I am using CodeIgniter.

Here's my code when the search button is clicked:

//search
        $('#search-btn').on('click',function(){

            var query = $("#keyword").val();

            var image = "<?php echo base_url()."/resources/loading/loading43.gif"; ?>";

            $('#loading').html(' + image + ');

            var query_url = "<?php echo site_url('item_controller/searchItem'); ?>";

            $.ajax({

                type:'POST',
                url: query_url,
                data:{query: $("#keyword").val()},
                dataType:'json',
                async: false,
                success:function(d){

                    //$('.display').dataTable().fnDestroy( true );

                    $("#example tbody").html(""); //HERE'S MY PROBLEM, DOESN'T DISPLAY LOADER WHEN SEARCHING

                    for(i in d){

                        $("#example tbody").append("<tr><td style='text-align: center; color:' data-code='TRUE'>" + d[i]['item_code'] + "</td><td style='text-align: left' data-name='TRUE'>" + d[i]['item_name'] + "</td><td><div style='text-align: center'><input type='button' value='ADD' class='k-button' id='" + d[i]['item_code'] + "' data-item=TRUE /></div></td></tr>");

                    }

                    //$("#search_result").show('blind');

                    $("[data-item]").on('click',function(){

                        var code = $(this).parents('tr').find('[data-code]').html();
                        var name = $(this).parents('tr').find('[data-name]').html();
                        // console.log(code,name);
                        $("#grid1 tbody").append("<tr><td style='text-align: center; width: 20%'><input type='text' value=" + code + " readonly style='width:50px; background-color: transparent; border-style: none' id=code" + counter_code++ +" /></td><td style='text-align: center; width: 40%'><input type='text' style='width: 90%; background-color: transparent; border-style: none' value='" + name + "' id=item"+ counter_item++ +" readonly /></td><td style='text-align: center'><input type='text' name='qty[]' id=qty"+ counter_qty++ +" style='text-align: center; width: 50px;' /></td><td style='text-align: center'><div align='center'><select style='width:100px; display: block' name='unit[]' id=unit"+ counter_unit++ +" ><option value=''>----</option><option value='pc/pcs'>PC/PCS</option><option value='BOX/BOXES'>BOX/BOXES</option></select></div></td><td style='text-align: center'><input type='text' name='price[]' id=price"+ counter_price++ +" style='text-align: right; width: 100px;' onblur='' /></td><td style='text-align: center'><input type='text' name='total[]' id=total"+ counter_total++ +" style='font-family: courier; text-align: right; background-color: lightgray; color: red; width: 100px;' readonly='readonly' value='' /></td></tr>");

                        ComputeTotal();

                    });

                    $('.display').dataTable({
                        "bPaginate": true,
                        "bLengthChange": true,
                        "bFilter": true,
                        "bSort": true,
                        "bInfo": true,
                        "bAutoWidth": false,
                        "bDestroy": true,
                        "bJQueryUI": false,
                        "bRetrieve": true,
                        "sPaginationType": "full_numbers",
                        "iDisplayLength": 25,
                        "destroy": true
                    });

                    //$('.display').dataTable().fnDestroy(true);

                    //$('.display').children().remove()

                },

            });    

        });

Here's the search form

<div id="loading"></div>

<div id="search_result" class="k-content">
     <div class="k-header" id="item-view-list" align="center">

        <table border="0" style="width: 80%; align: left" cellpadding="10" cellspacing="10" align="left">
            <tr>
                <td colspan="3">
                    <h5>SEARCH ITEM</h5>
                </td>
            </tr>
            <tr>
                <td style="width: 3%">
                    <label>Name/Description</label>
                </td>
                <td style="width: 40%">
                    <input type="text" name="keyword" id="keyword" style="width: 80%" /> <input type="button" value="SEARCH" id="search-btn" class="k-button" style="font-size: 12px" />
                </td>
            </tr>
        </table>

        <hr />

        <table cellpadding="0" cellspacing="0" border="0" class="display" id="example" style="font-size:small; width: 100%">
            <thead>
                <tr>

                </tr>
                <tr>
                    <th>CODE</th>
                    <th>NAME/DESCRIPTION</th>
                    <th></th>
                </tr>
            </thead>
            <tbody>

            </tbody>
        </table>
        <br />

    </div>
</div>

Answer 1

You could do as,

HTML

<div class="loader">
   <center>
       <img class="loading-image" src="loading.jpg" alt="loading..">
   </center>
</div>

CSS

.loading-image {
  position: absolute;
  top: 50%;
  left: 50%;
  z-index: 10;
}
.loader
{
    display: none;
    width:200px;
    height: 200px;
    position: fixed;
    top: 50%;
    left: 50%;
    text-align:center;
    margin-left: -50px;
    margin-top: -100px;
    z-index:2;
    overflow: auto;
}

In you js

Before the ajax call as,

$.ajax({
  // your ajax code
  beforeSend: function(){
       $('.loader').show()
   },
  complete: function(){
       $('.loader').hide();
  }
});

Answer 2

try this code.

$.ajax({
    type:'POST',
    url: query_url,
    data:{query: $("#keyword").val()},
    dataType:'json',
    async: false,
    success:function(d){
        // Your code.
    },
    beforeSend: function(){
        // Code to display spinner
    },
    complete: function(){
        // Code to hide spinner.
    }
});

refer this link to get more details. Ajax Events