Toggle Checkboxes on/off

You can write:

$(document).ready(function() {
    $("#select-all-teammembers").click(function() {
        var checkBoxes = $("input[name=recipients\\[\\]]");
        checkBoxes.prop("checked", !checkBoxes.prop("checked"));
    });                 
});

Before jQuery 1.6, when we only had attr() and not prop(), we used to write:

checkBoxes.attr("checked", !checkBoxes.attr("checked"));

But prop() has better semantics than attr() when applied to "boolean" HTML attributes, so it is usually preferred in this situation.

//this toggles the checkbox, and fires its event if it has    

$('input[type=checkbox]').trigger('click'); 
//or
$('input[type=checkbox]').click(); 

I know this is old but the question was a bit ambiguous in that toggle may mean each checkbox should toggle its state, whatever that is. If you have 3 checked and 2 unchecked, then toggling would make the first 3 unchecked and the last 2 checked.

For that, none of the solutions here work as they make all the checkboxes have the same state, rather than toggle each checkbox's state. Doing $(':checkbox').prop('checked') on many checkboxes returns the logical AND between all .checked binary properties, i.e. if one of them is unchecked, the returned value is false.

You need to use .each() if you want to actually toggle each checkbox state rather than make them all equal, e.g.

   $(':checkbox').each(function () { this.checked = !this.checked; });

Note that you don't need $(this) inside the handler as the .checked property exists in all browsers.