A neat JS function that you can use with Ghost Inspector to check if a checkbox/radio button is checked, and it also gives a visual feedback (like the native ones from other checks)

Ghost Inspector - checkbox state checker v2

function GI_itemHaveCheckedState(element, state, delay) {
    var valid = element.checked === state;
    if ( valid ) {
        if ( ! delay ) delay = 0;
        setTimeout(function() {
            element.style.outline = '5px solid rgba(98, 191, 103, 1)';
            setTimeout(function() {
                element.style.outline = 'initial';
            }, 500);
        }, delay);
    }
    return valid;
}
// Usage
return GI_itemHaveCheckedState(document.getElementById('checkbox-1'), true);
return GI_itemHaveCheckedState(document.getElementById('checkbox-2'), false);