JS 昵称，手机号，邮箱判断

 <script type="text/javascript">
var leyou = document.getElementById('J-leyou'),
    _name = document.getElementById('J-name'),
    mobile = document.getElementById('J-mobile'),
    email = document.getElementById('J-email');

leyou.onsubmit = function() {
    console.log(_name.value);
    if (_name.value === '') {
    alert('昵称不能为空');
    return false;
    }

    if (mobile.value === '') {
    alert('手机号码不能为空');
    return false;
    } else if (mobile.value.length < 11 || !/^(13[0-9]|15[0|3|6|7|8|9]|18[8|9])\d{8}$/.test(mobile.value)) {
    alert('手机号码格式不正确，请重新填写。');
    return false;
    }

    if (email.value === '') {
    alert('E-mail 不能为空');
    return false;
    } else if (!/^([a-zA-Z0-9_-])+@([a-zA-Z0-9_-])+((\.[a-zA-Z0-9_-]{2,3}){1,2})$/.test(email.value)) {
    alert('E-mail 格式不正确，请重新填写。');
    return false;
    }
};
        </script>