There was a question I just ran across on Stack Overflow asking how to set a hidden input with js, and also to restrict access to one form from another. Setting the hidden input value is pretty simple, and I figured this would be a breeze. Overall it was, but I scrapped the guys code and rewrote it from scratch. It was easier for me to do that than to figure out his code. I wanted to share what I did here:

It isn’t the most robust thing, but it works. Once you select one answer on form A or B, you have to select only from that form. Annoying alerts are used, but it is just a prototype – the real deal would need to be much slicker.

I added simple validation; if there aren’t 3 checked radio buttons the form is not complete. Also, the validation triggers the submit button enable, so it’s a two-fer
🙂

Here is the code (in case jsFiddle ever blows up):

<h2>Table A</h2>
<table id="tableA" border="1">
    <tr>
        <td>
            A1
        </td>
        <td>
            <input type="radio" name="a1" value="1" /> Yes
            <input type="radio" name="a1" value="0" /> No
        </td>
    </tr>
    <tr>
        <td>
            A2
        </td>
        <td>
            <input type="radio" name="a2" value="1" /> Yes
            <input type="radio" name="a2" value="0" /> No
        </td>
    </tr>
    <tr>
        <td>
            A3
        </td>
        <td>
            <input type="radio" name="a3" value="1" /> Yes
            <input type="radio" name="a3" value="0" /> No
        </td>
    </tr>
</table>

<h2>Table B</h2>
<table id="tableB" border="1">
    <tr>
        <td>
            B1
        </td>
        <td>
            <input type="radio" name="b1" value="1" /> Yes
            <input type="radio" name="b1" value="0" /> No
        </td>
    </tr>
    <tr>
        <td>
            B2
        </td>
        <td>
            <input type="radio" name="b2" value="1" /> Yes
            <input type="radio" name="b2" value="0" /> No
        </td>
    </tr>
    <tr>
        <td>
            B3
        </td>
        <td>
            <input type="radio" name="b3" value="1" /> Yes
            <input type="radio" name="b3" value="0" /> No
        </td>
    </tr>
</table>

<p>
    <button id="submit">Submit</button>
    <button id="reset">Reset</button>
</p>

<input type="hidden" id="activeTable" />
​

window.ns = {};
ns.activeTable = null;
ns.validate = function() {
    // Simple validation
    // If we don't have 3 checked radio buttons, it is invalid
    var checked = $("#" + ns.activeTable).find("input[type=radio]:checked");
    var valid = (checked || []).length === 3;
    $("#submit").prop("disabled", !valid);
    return valid;
};

ns.validate();

$("#submit").click(function() {
    var valid = ns.validate;
    if (valid == false) {
        alert("You must complete the form!");
        return;
    }
    
    var results = $("#" + ns.activeTable).find("input[type=radio]:checked");
    var output = ns.activeTable + " Results\n";
    $.each(results, function(idx, data) {
        output += "\t" + $(this).prop("name") + 
            " - " + $(this).val() + "\n";
    });
    alert(output);
    $("#activeTable").val(ns.activeTable);
});

$("#reset").click(function() {
    $("input[type=radio]").prop("checked", false);
    ns.activeTable = null;
    ns.validate();
});

$("input[type=radio]").click(function() {
    var selectedTable = $(this).closest("table");
    if (ns.activeTable != null && 
        selectedTable.prop("id") != ns.activeTable) {
        alert("Invalid form selection. Onlye selections from " + 
              ns.activeTable + " are allowed");
        $(this).prop("checked", false);
    } else {
        ns.activeTable = selectedTable.prop("id");
    }
    ns.validate();
});​

html { margin: 10px; }
table { width: 100%; border-collapse: collapse; margin-bottom: 20px; }
table td { border: 3px solid #CCC; padding: 5px; }
table td:nth-child(1) { width: 75%; }
table td:nth-child(2) { text-align: center; }
h2 { font-size: 1.8em; font-weight; bold }
button { padding: 5px; border-radius: 15px; background-color: #CCC; 
         width: 100px; }​