Using Jquery to add items in Listbox from Textbox

Question

I am stuck somewhere using jquery to append the list box from a text box.

here is my jquery

  $("#btnAddSvc").click(function () {
        var svc = $("#<%= txtServiceName.ClientID %>").val();  //Its Let you know the textbox's value   
        svc.appendTo("#<%=lstSvcName.ClientID %>");
    }); 

I am using asp.net (c#) to develop my code

<asp:Button ID="btnAddSvc" runat="server" Text=">>" Font-Size="Medium" />
<asp:ListBox ID="lstSvcName" runat="server" SelectionMode="Multiple" ToolTip="Selected Service Names"
                Width="169px"></asp:ListBox>

can someone please help as i am not able to get the values in list box.

Answer 1

The jQuery selector $() is missing for "#<%=lstSvcName.ClientID %>" so you will get id of lstSvcName instead of object .

I also changed the append statement as it does not have correct syntax.

"#<%=lstSvcName.ClientID %>"

would be

$("#<%=lstSvcName.ClientID %>")

Your code will become

$("#<%= btnAddSvc.ClientID %>").click(function () {
      var svc = $("#<%= txtServiceName.ClientID %>").val();  //Its Let you know the textbox's value   
      $("#<%=lstSvcName.ClientID %>").append('<option value="'+svc+'">item '+svc+'</option>');
      return false;
}); 

EDIT [ More functionality requested by OP for unique items in ListBox and clearing TextBox]

$("#<%= btnAddSvc.ClientID %>").click(function () {
    var txt = $("#<%= txtServiceName.ClientID %>");
    var svc = $(txt).val();  //Its Let you know the textbox's value   
    var lst = $("#<%=lstSvcName.ClientID %>");
    var options = $("#<%=lstSvcName.ClientID %> option");
    var alreadyExist = false;
    $(options).each(function () {
        if ($(this).val() == svc) {
            alert("Item alread exists");
            alreadyExist = true;
            return;
        }
        txt.val("");
        // alert($(this).val());
    });
    if(!alreadyExist)
            $(lst).append('<option value="' + svc + '">' + svc + '</option>');
    return false;
});

Answer 2

You could do it using jquery manipulating the DOM but... Now there's a more elegant way to do it: an object-oriented way (using a MVVM - Model View ViewModel), using knockoutjs

Knockoutjs Nuget Package

You create a binding to your list just adding data-bind="options: elements" to your list, and you are always working with objects, never with DOM elements, in this example I have a string array but you can create custom objects and bind them using just a little variation in the syntax

The way to do it is:

<script type="text/javascript" src="Scripts/jquery-1.7.2.min.js"></script>
<script type="text/javascript" src="Scripts/knockout-2.1.0.js"></script>
<script type="text/javascript">
    $(function () {
        var model = {
            elements: ko.observableArray(),
            addElement: function () {
                this.elements.push($("#<%= this.newElement.ClientID %>").val());
            }
        };

        ko.applyBindings(model);
    });
</script>


    <asp:ListBox runat="server" ID="myListbox" Rows="10" Width="25%" data-bind="options: elements">
    </asp:ListBox>
    <br />
    <asp:TextBox runat="server" ID="newElement"></asp:TextBox>
    <input type="button" id="addElement" value="Add element" data-bind="click: addElement" />

This is the output:

Answer 3

Try something like this. This may help you. Change the return value for your convenience.

   $('#<%= btnAddSvc.ClientID %>').click(function () {
            $textbox = $('#<%= txtServiceName.ClientID %>');
            $listbox = $('#<%= lstSvcName.ClientID %>');
            $listbox.append($('<option></option>').attr('value', $textbox.val()).text($textbox.val()));
            return false;
        });