How to make the "select all" checked by default on page load for sumoselect jquery

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I am using Sumoselect jquery for populating the dropdown list in my ASP.Net WebForms page, but on page load I am unable to make the selection "Select All" checked so that all the dropdowns values were being selected on page load.

What I have tried:

This is my aspx code---

<%@ Page Language="C#" AutoEventWireup="true" Inherits="Dropdown1" CodeBehind="Dropdown1.aspx.cs" %>

<!DOCTYPE html>

<html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1" runat="server">
    <title></title>
    <script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.9.0/jquery.min.js"></script>
    <script type="text/javascript" src="jquery.sumoselect.min.js"></script>
    <link href="sumoselect.css" rel="stylesheet" />

    <script type="text/javascript">

        $(document).ready(function () {
            $('#<%=lstBoxTest.ClientID%>').SumoSelect({selectAll:true});
        });


    </script>
    <style type="text/css">
        body {
            font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif;
            color: #444;
            font-size: 13px;
        }

        p, div, ul, li {
            padding: 0px;
            margin: 0px;
        }
    </style>
</head>
<body>
    <form id="form1" runat="server">
        <asp:ListBox runat="server" ID="lstBoxTest" SelectionMode="Multiple">
            <asp:ListItem Text="Red" Value="0"></asp:ListItem>
            <asp:ListItem Text="Green" Value="1"></asp:ListItem>
            <asp:ListItem Text="Yellow" Value="2"></asp:ListItem>
            <asp:ListItem Text="Blue" Value="3"></asp:ListItem>
            <asp:ListItem Text="Black" Value="4"></asp:ListItem>
        </asp:ListBox>
        <asp:Button Text="Get Values" Visible="false" ID="btnGetSelectedValues" OnClick="btnGetSelectedValues_Click" runat="server" />
    </form>
</body>
</html>

and this is my code behind---

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;


    public partial class Dropdown1 : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {


        }


        protected void btnGetSelectedValues_Click(object sender, EventArgs e)
        {
            string selectedValues = string.Empty;



            foreach (ListItem li in lstBoxTest.Items)
            {
                if (li.Selected == true)
                {
                    selectedValues += li.Text + ",";
                }
            }

            
            Response.Write(selectedValues.ToString());
        }



    }

Posted 15-Dec-17 22:59pm

Member 13440616

Updated 1-Nov-18 9:17am

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Richard Deeming · Answer 1 · 2017-12-18T07:53:00

Looking at the documentation[^], you need to call the selectAll method:

$('#<%=lstBoxTest.ClientID%>').SumoSelect({selectAll:true})[0].sumo.selectAll();

However, this will overwrite the user's selection every time they press the button. You'll want to make sure you only call the selectAll method on the first load, or when no items are selected. For example:

JavaScript

$(function(){
    var list = $('#<%=lstBoxTest.ClientID%>');
    list.SumoSelect({selectAll:true});
    
    if (!list.find("option:selected").length) {
        // No items are selected:
        list[0].sumo.selectAll();
    }
});

Laxmidhar tatwa technologies · Answer 2 · 2017-12-18T04:03:00

 <script>  
       function selectDeselect() {
          
           var listb = document.getElementById('<%=lstBoxTest.ClientID %>');  
          
            var len = listb.options.length;  
            for (var i = 0; i < len; i++) {  
                
                listb.options[i].selected = true;  
            }  
        }  
        
      </script>  
    <style type="text/css">
        body {
            font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif;
            color: #444;
            font-size: 13px;
        }
 
        p, div, ul, li {
            padding: 0px;
            margin: 0px;
        }
    </style>
</head>
<body onload="selectDeselect();">
    <div style="margin-left:200px;">
    <form id="form1" runat="server">
        <asp:ListBox runat="server" ID="lstBoxTest" SelectionMode="Multiple" Width="300px">
            <asp:ListItem Text="Red" Value="0"></asp:ListItem>
            <asp:ListItem Text="Green" Value="1"></asp:ListItem>
            <asp:ListItem Text="Yellow" Value="2"></asp:ListItem>
            <asp:ListItem Text="Blue" Value="3"></asp:ListItem>
            <asp:ListItem Text="Black" Value="4"></asp:ListItem>
        </asp:ListBox>
        <asp:Button Text="Get Values" Visible="false" ID="btnGetSelectedValues" OnClick="btnGetSelectedValues_Click" runat="server" />
    </form>
        </div>
</body>

Member 14040885 · Answer 3 · 2018-11-01T09:18:00

Solution 3

$( document ).ready(function() {

var list = $('#<%=cyclst.ClientID%>');
list.SumoSelect({selectAll:true});

if (!list.find("option:selected").length) {
// No items are selected:
list[0].sumo.selectAll();
}
});

This is working for me.

Posted 1-Nov-18 9:18am

Member 14040885

Updated 1-Nov-18 9:19am

v2

Comments

CHill60 2-Nov-18 9:17am

This is Solution 2 reposted