Question

Im confused why this isnt working and am not able to debug

I have a set of checkboxe’s grouped by an attribute value
and have a checkall class at the foot of each group with matching attribute value when i click this i want to toggle the other checkboxs to same state

jquery

$(function () {
    $('.checkall').click(function () {
        var myactivemonth=$(this).attr("data-mymonth");
        console.log(myactivemonth);
        var myactivebox="a_"+myactivemonth;
        $('checkbox[data_mymonth=myactivemonth]').attr('checked','checked');
});

html

<input id="alloInv" class="tip_trigger" type="checkbox" data-mymonth="a_October2012" title="13.94" value="2018441" name="alloInv">
<input id="alloInv" class="tip_trigger" type="checkbox" data-mymonth="a_October2012" title="10.94" value="201845" name="alloInv"> 
<input class="checkall" type="checkbox" data-mymonth="October2012">

IT appears all ok but the boxes aren’t ticking 🙁

Answer 1

You have a series of wrong things

1. checkbox should be :checkbox
2. data_mymonth should be data-mymonth
3. myactivebox needs to be passed dynamically
4. from the code in the question you are missing the final });

A couple of improvements as well

1. you should use .prop() instead of .attr() for actual properties of the element. $(this).data('mymonth');
2. use .data() to retrieve values from data- attributes

So

$(':checkbox[data-mymonth="' + myactivebox + '"]').prop('checked',true);

Working demo at http://jsfiddle.net/6Nv3N/

---

Update

I missed the toggle part of your question

To handle toggling the checkboxes you need to set the checked property to that of the .checkall element.

The .prop() way (demo)

$(':checkbox[data-mymonth="' + myactivebox + '"]').prop('checked', this.checked);

---

The .attr() way

$(':checkbox[data-mymonth="' + myactivebox + '"]').attr('checked', this.checked);