使用必需的复选框验证来防止表单提交

您需要在提交时向表单中添加事件

document.getElementsByName("subscribe").onsubmit(function(event) {
    if(!isChecked) { //If not checked
        event.preventDefault(); // stops the form submitting
    }
});

如果未选中复选框 preventDefault 。这将阻止表单提交

你能做到的 return

<form onsubmit="return valthis()" action="//mailchimp form" method="post" id="mc-embedded-subscribe-form" name="mc-embedded-subscribe-form" class="validate" target="_blank" novalidate>

<script>
function valthis() {
    var checkBoxes = document.getElementsByClassName( 'myCheckBox' );
    var isChecked = false;

    for (var i = 0; i < checkBoxes.length; i++) {
        if ( checkBoxes[i].checked ) {
            isChecked = true;
            break; //don't need to continue the loop once a checkbox was found
        }
    }

    if ( !isChecked ) {
        alert( 'At least one checkbox is NOT checked!' );
        return false;
    }

    return true;
}
</script>

<input type="submit" value="Subscribe to notifications" name="subscribe" id="mc-embedded-subscribe" class="button">