Question

I’m attempting to disable a radio button from an asp RadioButtonList using JavaScript. Here is what I have:

<asp:RadioButton ID="rbPlanner" runat="server" onclick="deselectRadioListItem('P');" />

which calls this client JavaScript onClick…

function deselectRadioListItem(radioValue) {
    var clientID = ('<%= rblSummaryOptions.ClientID %>');
    for (i = 0; i < '<%= rblSummaryOptions.Items.Count %>'; i++) {
        if (document.getElementById(clientID + "_" + i.toString()).value == radioValue) {
            (clientID + "_" + i.toString()).disabled === true;
        }
        else
        {
            (clientID + "_" + i.toString()).disabled === false;
        }
    }
}

Everything appears to be working correctly (fires, iterates, if-statements work) however, the radiobutton control is not becoming disabled, even though the logic is hit. What am I missing? Help is much appreciated!

Answer 1

The === operator is used for comparison. You need to use =.

function deselectRadioListItem(radioValue) {
    var clientID = ('<%= rblSummaryOptions.ClientID %>');
    for (i = 0; i < '<%= rblSummaryOptions.Items.Count %>'; i++) {
        if (document.getElementById(clientID + "_" + i.toString()).value == radioValue) {
            document.getElementById(clientID + "_" + i.toString()).disabled = true;
        }
        else
        {
            document.getElementById(clientID + "_" + i.toString()).disabled = false;
        }
    }
}

Or cleaned up a tiny bit:

function deselectRadioListItem(radioValue) {
    var clientID = ('<%= rblSummaryOptions.ClientID %>');
    for (i = 0; i < '<%= rblSummaryOptions.Items.Count %>'; i++) {
        var objCurrentRdo = document.getElementById(clientID + "_" + i.toString());

        if (objCurrentRdo.value == radioValue)
            objCurrentRdo.disabled = true;
        else
            objCurrentRdo.disabled = false;
    }
}​

Additional Information: Check out Comparison Operators on MDN.