Since I don't see the jQuery tag in the OP, here is a javascript only option :
document.addEventListener("DOMContentLoaded", function (event) {
var _selector = document.querySelector('input[name=myCheckbox]');
_selector.addEventListener('change', function (event) {
if (_selector.checked) {
// do something if checked
} else {
// do something else otherwise
}
});
});
See JSFIDDLE