javascript - 每个 div 内必须至少选中一个复选框

Question

HTML代码

<div class="answer">
    <input type="checkbox" />
    <input type="checkbox" />
    <input type="checkbox" />
    <input type="checkbox" />
</div>
<div class="answer">
    <input type="checkbox" />
    <input type="checkbox" />
    <input type="checkbox" />
    <input type="checkbox" />
</div>
<button>check</button>

jQuery 代码

$('button').click(function(){

    var checkedboxes = $('.answer :checkbox:checked').length;

    if (checkedboxes === 0){
        alert('At least 1 checkbox must be checked from this div!');
    }
});

但我的代码不会在每个 <div class='answer'> 内检查至少一个复选框检查

JS FIDDLE DEMO

Answer 1

尝试，

if ($('.answer').filter(function(){  return $(this).find(':checked').length === 0 }).length > 0 ) {
 alert('At least 1 checkbox must be checked from this div!');
}

DEMO