为什么验证不适用于所有PC浏览器？

Question

以下验证码在所有MAC浏览器上均可100％运行。但是在所有PC浏览器上都会忽略验证。用户提交表单后，将验证电子邮件并返回一条感谢信息。有没有理由说它在PC浏览器上不起作用？

function validateModalForm(modalemail) {
    var regexp = /^[\w-\.]{1,}\@([\da-zA-Z-]{1,}\.){1,}[\da-zA-Z-]{2,3}$/;
    return regexp.test(modalemail);
}

$(document).ready(function() {

    var clearMePrevious = "";

    // clear input on focus
    $("#modalemail").focus(function() {
        if ($(this).val() == $(this).attr("title")) {
            clearMePrevious = $(this).val();
            $(this).val("");
        }
    });

    // if field is empty afterward, add text again
    $("#modalemail").blur(function() {
        if ($(this).val() == "") {
            $(this).val(clearMePrevious);
        }
    });


    $('#submitmodalemail').click(function() {
        if (!validateModalForm($(modalemail).val())) {
            $("#modal_error").html("Invalid Email. Try again.");
            return false;
        }
        app.ajax.load({
            reqName: 'emailSubmit',
            url: "$httpUrl('Bronto - OptIn')$?email=" + $('#modalemail').val(),
            selector: '#modalemailbox',
            callback: function(responseText, textStatus) {}
        });
        return false;
    });

});

<form id="emailsignup_modal" name="emailsignup_modal" method="post"     action="$httpUrl('Bronto-OptIn', 'fid', 'information')$">
<input class="email_field" type="text" title="Enter Your Email Address" value="Enter Your Email Address" name="email" id="modalemail" />
<button class="email-signup-btn" value="Submit" name="submitmodalemail" id="submitmodalemail"></button>
</form>

<div id="modal_error"></div>
<div class="privacy"><a href="Page-Show?cid=privacy-policy" target="_blank" title="Privacy Policy">Privacy Policy.</a> *Offer valid for first-time subscribers only.</div>
</div>
</div>