I have two list boxes(A,B) with some values and i can send values from A to B or B to A

Question

I have two list boxes(A,B) with some values and i can send values from A to B or B to A and i have one save button.

For the first time without updating any list box if i click on save button i am showing message like "NO changes or Done"

But once i send one item from A to B and again sending that same item from B to A it means no changes or Done. here also i want to show same message "NO changes or Done" .but i am unable to fine the staus can any one pleasse give code or tips to find the default status for listboxs in javascript.

Thanks

Answer 1

I dont know why you want to do this with client side javascript, but here is an example: lbClicked is a js-function which is called onclick on the listboxes' items to remove the items and add them to the other listbox. The most important is that i have registered two javascript-arrays on serverside(Lb1Items and Lb2Items), they hold the values of the listboxes' items. When the user clicks the submit button(or what ever) i compare each listbox with the corresponding array. When all is the same nothing was changed.

 function lbClicked(sender){
        var lb1=document.getElementById("ListBox1");
        var lb2=document.getElementById("ListBox2");
        if(lb1 != null && lb2 != null){
            if(sender==lb1){
                var selectedItem=lb1.item(lb1.selectedIndex);
                if(! contains(Lb2Items,selectedItem.value)){
                   lb1.remove(lb1.selectedIndex);
                   lb2.add(selectedItem);
                }
            }else if(sender==lb2){
                var selectedItem=lb2.item(lb2.selectedIndex);
                if(! contains(Lb1Items,selectedItem.value)){
                   lb2.remove(lb2.selectedIndex);
                   lb1.add(selectedItem);
                }
            }
        }
    }


    function Button1_onclick() {
        var changed=itemsChanged();
        if(changed)
            alert("Items Changed!");
        else
            alert("Items not changed!");
        return changed;
    }

    function itemsChanged(){
        if(Lb1Items != null && Lb2Items != null){
            var lb1=document.getElementById("ListBox1");
            var lb2=document.getElementById("ListBox2");
            if(lb1 != null && lb2 != null){
                if(lb1.options.length != Lb1Items.length || lb2.options.length != Lb2Items.length)
                    return true;

                for(var i=0; i<lb1.options.length; i++){
                    var item=lb1.options[i];
                    if(! contains(Lb1Items,item.value))
                        return true;
                }
                for(var i=0; i<lb2.options.length; i++){
                    var item=lb2.options[i];
                    if(! contains(Lb2Items,item.value))
                        return true;
                }
            }
        }
        return false;
    }

    function contains(objArray,objectToFind){
        for(var i=0;i<objArray.length;i++){
               if(objArray[i]==objectToFind)
                   return true;
        }
        return false;
    }

Tested with ASP.Net:

<form id="form1" runat="server">
        <asp:ListBox ID="ListBox1" runat="server" onclick="javascript:lbClicked(this);" Height="84px">
           <asp:ListItem Text="Item 1" Value="1"></asp:ListItem>
            <asp:ListItem Text="Item 2" Value="2"></asp:ListItem>
            <asp:ListItem Text="Item 3" Value="3"></asp:ListItem>
            <asp:ListItem Text="Item 4" Value="4"></asp:ListItem>
            <asp:ListItem Text="Item 5" Value="5"></asp:ListItem>
        </asp:ListBox>&nbsp;
        <asp:ListBox ID="ListBox2" runat="server" onclick="javascript:lbClicked(this);" Height="82px">
            <asp:ListItem Text="Item 6" Value="6"></asp:ListItem>
            <asp:ListItem Text="Item 7" Value="7"></asp:ListItem>
            <asp:ListItem Text="Item 8" Value="8"></asp:ListItem>
            <asp:ListItem Text="Item 9" Value="9"></asp:ListItem>
            <asp:ListItem Text="Item 10" Value="10"></asp:ListItem>
        </asp:ListBox>
        &nbsp;
        <input id="Button1" type="button" value="button" onclick="return Button1_onclick()" />
    </form>

and the array were registered on server-side this way:

 ClientScript.RegisterArrayDeclaration("Lb1Items", "1,2,3,4,5")
 ClientScript.RegisterArrayDeclaration("Lb2Items", "6,7,8,9,10")

Regards, Tim

EDIT: added check for identical number of items in itemsChanged-function and check if target listbox already contains the item to transfer