Smallest code possible to filter checkboxlist through javascript

Asked 6/9, 2011 at 7:4 Answered 7/9, 2011 at 7:18

Solved javascript asp.net search controls checkboxlist

Project doesn't need any javascript libraries such as jQuery, Dojo, Prototype so there is no easy way i suppose. I would like to have in-depth answers for the question explaining how would one do this. As most of you might know asp.net checkboxlist emits a markup like below in Flow repeatLayout.

<span>
<checkbox><label></br>
<checkbox><label></br>
<checkbox><label></br>
</span>

i haven't put the ending/closing tags for simplicity. We have a textbox for searching through this list of checkbox.Now comes the question,

How would i Filter the checkboxlist when user types the search term in the textbox and hide the unmatched checkbox+label.

some more questions i would like getting answers for that are related to above

Is there any ready made STANDALONE script for this purpose?
Is there a pattern , article, post explaining the glitches, points to remember while providing search functionality? something like onkeydown don't do this,
My Idea right now would be have a cached collection of label tags innerHTML then loop through each tag and check for search term, when found hide all others but show only matching.[My Concern is what will happen when list is too long, on every keypress looping is not the best idea i suppose]

Your suggestions, answers, solution, scripts are welcome

Hambletonian answered 6/9, 2011 at 7:4 Comment(0)

This solution is based on Ktash's answer. I made it cause I want to learn more about javascript, DOM navigating and RegExp.

I changed "keypress" event with "keydown" since the previous doesn't trigger on backspace/delete so deleting all the characters with backspace/delete still left the list filtered.

[Default.aspx]

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

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
  <title></title>
  <script type="text/javascript">
    window.onload = function () {
      var tmr = false;
      var labels = document.getElementById('cblItem').getElementsByTagName('label');
      var func = function () {
        if (tmr)
          clearTimeout(tmr);
        tmr = setTimeout(function () {
          var regx = new RegExp(document.getElementById('inputSearch').value);
          for (var i = 0, size = labels.length; i < size; i++)
            if (document.getElementById('inputSearch').value.length > 0) {
              if (labels[i].textContent.match(regx)) setItemVisibility(i, true);
              else setItemVisibility(i, false);
            }
            else
              setItemVisibility(i, true);
        }, 500);

        function setItemVisibility(position, visible)
        {
          if (visible)
          {
            labels[position].style.display = '';
            labels[position].previousSibling.style.display = '';
            if (labels[position].nextSibling != null)
              labels[position].nextSibling.style.display = '';
          }
          else
          {
            labels[position].style.display = 'none';
            labels[position].previousSibling.style.display = 'none';
            if (labels[position].nextSibling != null)
              labels[position].nextSibling.style.display = 'none';

          }
        }
      }

      if (document.attachEvent) document.getElementById('inputSearch').attachEvent('onkeypress', func);  // IE compatibility
      else document.getElementById('inputSearch').addEventListener('keydown', func, false); // other browsers
    };
  </script>
</head>
<body>
  <form id="form1" runat="server">
  <table>
    <tr>
      <td>
        <asp:TextBox runat="server" ID="inputSearch" ClientIDMode="Static" />
      </td>
    </tr>
    <tr>
      <td>
        <asp:CheckBoxList runat="server" ID="cblItem" ClientIDMode="Static" RepeatLayout="Flow" />
      </td>
    </tr>
  </table>
  </form>
</body>
</html>

[Default.aspx.cs]

using System;
using System.Collections.Generic;

namespace RealtimeCheckBoxListFiltering
{
    public partial class Default : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            cblItem.DataSource = new List<string>() { "qwe", "asd", "zxc", "qaz", "wsx", "edc", "qsc", "esz" };
            cblItem.DataBind();
        }
    }
}

Bergwall answered 7/9, 2011 at 7:18 Comment(5)

@Razvan that's exhaustive enough to be marked as answer. But credit goes to Ktash – Hambletonian 7/9, 2011 at 8:15

I gave him a +1 cause he came with the basic ideea :) that setTimeout/clearTimeout does the trick – Avicenna 7/9, 2011 at 8:17

@Razvan i saw your comment previous to commenting on this answer – Hambletonian 7/9, 2011 at 8:22

Looks good. My only comment is that you use element.textContent when IE 8 and below don't support that fully. For IE 8 and below support, you'll want to make the element visible, and then do var txt = element.textContent || element.innerText to get the text value across browser. – Saville 7/9, 2011 at 15:8

@Ktash: Yeah, I used only textContent cause I didn't understood that part in your code :) Now I know it was from compatibility. Thanks! :) – Avicenna 7/9, 2011 at 19:54

var tmr = false;
var labels = document.getElementsByTagName('label')
var func = function() {
    if (tmr) clearTimeout(tmr);
    tmr = setTimeout(function () {
        var regx = new Regex(inputVal); /* Input value here */
        for(var i = 0, size = labels.length; i < size; i++) {
            if(regx.match(labels[i].textContent || labels[i].innerText)) labels[i].style.display = 'block';
            else labels[i].style.display = 'none';
        }
    }, 100);
}
if (document.attachEvent) inputField.attachEvent('onkeypress', func);
else inputField.addEventListener('keypress', func, false);

Not perfect, and not all the way complete, but it should get you started on it. There is a 100 millisecond delay before it performs the loop so that it won't run on every keypress, but likely just after they've stopped typing. Probably want to play with the value a bit as you see fit, but it gives you the general idea. Also, I didn't set the variables for inputField nor inputVal, but those I assume you would already know how to grab. If your labels are not a static list onload, you'll probably want to get the list every time.

Saville answered 6/9, 2011 at 7:21 Comment(1)

well this did lead me in right way. Do you recommend any pattern for the same(i mean design pattern) Also i will wait until i get further answers – Hambletonian 6/9, 2011 at 8:13

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