CheckBoxList Items using JavaScript

Question

I have a checkoxlist with a couple of items and an all option. The user can select all and I want this to check off all the options and if they uncheck all it will uncheck all options.

I have accomplished this with the following code.

<script language="javascript" type="text/javascript">
    function CheckBoxListSelect(cbControl) //, state)
    {
        var chkBoxList = document.getElementById(cbControl);
        var chkBoxCount= chkBoxList.getElementsByTagName("input");

        alert(chkBoxCount[0].checked);

        for(var i=0;i<chkBoxCount.length;i++)
        {   
            chkBoxCount[i].checked = chkBoxCount[0].checked //state;
        }

        return false; 
    }
</script>

cblAffiliation.Attributes.Add("onclick", "javascript: CheckBoxListSelect ('" & cblAffiliation.ClientID & "');")

The issue is that if I select any of the boxes it loops through and then sets them to whatever the all option is. I am having trouble figuring out the best way to get around this.

I want to avoid using a checkbox next to the checkboxlist, then I have to make that line up with the checkboxlist.

Answer 1

Simply check to see if the box clicked was the all option. If it was, then go ahead and change the rest of the boxes. If it isn't, then check all the options to see if they are all checked so you can update the 'All' checkbox.

---

EDIT

You might want to use onChange, instead of onClick, onClick will probably be called before the value on the given checkbox is changed.

---

Code not checked, please forgive syntax problems.

<script language="javascript" type="text/javascript">
    function CheckBoxListSelect(cbControl) //, state)
    {
        var chkBoxList = document.getElementById(cbControl);
        var chkBoxCount= chkBoxList.getElementsByTagName("input");
        var clicked = this;

        alert(chkBoxCount[0].checked ? 'All is Checked' : 'All is not Checked');
        alert(clicked == chkBoxCount[0] ? 'You Clicked All' : 'You Didn't click All');

        var AllChecked = true; // Check the all box if all the options are now checked

        for(var i = 1;i < chkBoxCount.length; i++)
        {   
            if(clicked == chkBoxCount[0]) { // Was the 'All' checkbox clicked?
                chkBoxCount[i].checked = chkBoxCount[0].checked; // Set if so
            }
            AllChecked &= chkBoxCount[i].checked; // AllChecked is anded with the current box
        }

        chkBoxCount[0].checked = AllChecked;

        return false; 
    }
</script>

cblAffiliation.Attributes.Add("onchange", "javascript: CheckBoxListSelect ('" & cblAffiliation.ClientID & "');")