Javascript 提交时停止表单刷新页面

当按下Send按钮时字段中没有任何数据时，我应该如何防止页面刷新？

验证设置工作正常，所有字段都变为红色，但随后页面立即刷新.我对JS的了解比较基础.

尤其是我认为底部的processForm()函数是"坏的".

HTML个

<form id="prospects_form" method="post">
    <input id="form_name" tabindex="1" class="boxsize" type="text" name="name" placeholder="Full name*" maxlength="80" value="" />
    <input id="form_email" tabindex="2" class="boxsize" type="text" name="email" placeholder="Email*" maxlength="100" value="" />
    <input id="form_subject" class="boxsize" type="text" name="subject" placeholder="Subject*" maxlength="50" value="FORM: Row for OUBC" />
    <textarea id="form_message" class="boxsize" name="message" placeholder="Message*" tabindex="3" rows="6" cols="5" maxlength="500"></textarea>

    <button id="form_send" tabindex="5" class="btn" type="submit" onclick="return processForm()">Send</button>
    <div id="form_validation">
        <span class="form_captcha_code"></span>
        <input id="form_captcha" class="boxsize" type="text" name="form_captcha" placeholder="Enter code" tabindex="4" value="" />
    </div>
    <div class="clearfix"></div>
</form>

JS

$(document).ready(function() { 

// Add active class to inputs
$("#prospects_form .boxsize").focus(function() { $(this).addClass("hasText"); });
$("#form_validation .boxsize").focus(function() { $(this).parent().addClass("hasText"); });
// Remove active class from inputs (if empty)
$("#prospects_form .boxsize").blur(function() { if ( this.value === "") { $(this).removeClass("hasText"); } });
$("#form_validation .boxsize").blur(function() { if ( this.value === "") { $(this).parent().removeClass("hasText"); } });



///////////////////
// START VALIDATION
$("#prospects_form").ready(function() {

    // DEFINE GLOBAL VARIABLES
    var valName = $('#form_name'),
        valEmail = $("#form_email"),
        valEmailFormat = /^(([^<>()[\]\\.,;:\s@\"]+(\.[^<>()[\]\\.,;:\s@\"]+)*)|(\".+\"))@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$/,
        valMsg = $('#form_message'),
        valCaptcha = $('#form_captcha'),
        valCaptchaCode = $('.form_captcha_code');



    // Generate captcha
    function randomgen() {
        var rannumber = "";
        // Iterate through 1 to 9, 4 times
        for(ranNum=1; ranNum<=4; ranNum++){ rannumber+=Math.floor(Math.random()*10).toString(); }
        // Apply captcha to element
        valCaptchaCode.html(rannumber);
    }
    randomgen();


    // CAPTCHA VALIDATION
    valCaptcha.blur(function() {
        function formCaptcha() {
            if ( valCaptcha.val() == valCaptchaCode.html() ) {
                // Incorrect
                valCaptcha.parent().addClass("invalid");
                return false;
            } else {
                // Correct
                valCaptcha.parent().removeClass("invalid");
                return true;
            }
        }
        formCaptcha();
    });

    // Remove invalid class from captcha if typing
    valCaptcha.keypress(function() {
        valCaptcha.parent().removeClass("invalid");
    });


    // EMAIL VALIDATION (BLUR)
    valEmail.blur(function() {
        function formEmail() {
            if (!valEmailFormat.test(valEmail.val()) && valEmail.val() !== "" ) {
                // Incorrect
                valEmail.addClass("invalid");
            } else {
                // Correct
                valEmail.removeClass("invalid");
            }
        }
        formEmail();
    });

    // Remove invalid class from email if typing
    valEmail.keypress(function() {
        valEmail.removeClass("invalid");
    });


    // VALIDATION ON SUBMIT
    $('#prospects_form').submit(function() {
        console.log('user hit send button');

        // EMAIL VALIDATION (SUBMIT)
        function formEmailSubmit() {
            if (!valEmailFormat.test(valEmail.val())) {
                // Incorrect
                valEmail.addClass("invalid");
            } else {
                // Correct
                valEmail.removeClass("invalid");
            }
        }
        formEmailSubmit();

        // Validate captcha
        function formCaptchaSubmit() {
            if( valCaptcha.val() === valCaptchaCode.html() ) {
                // Captcha is correct
            } else {
                // Captcha is incorrect
                valCaptcha.parent().addClass("invalid");
                randomgen();
            }
        }
        formCaptchaSubmit();


        // If NAME field is empty
        function formNameSubmit() {
            if ( valName.val() === "" ) {
                // Name is empty
                valName.addClass("invalid");
            } else {
                valName.removeClass("invalid");
            }
        }
        formNameSubmit();


        // If MESSAGE field is empty
        function formMessageSubmit() {
            if ( valMsg.val() === "" ) {
                // Name is empty
                valMsg.addClass("invalid");
            } else {
                valMsg.removeClass("invalid");
            }
        }
        formMessageSubmit();


        // Submit form (if all good)
        function processForm() {
            if ( formEmailSubmit() && formCaptchaSubmit() && formNameSubmit() && formMessageSubmit() ) {
                $("#prospects_form").attr("action", "/clients/oubc/row-for-oubc-send.php");
                $("#form_send").attr("type", "submit");
                return true;
            } else if( !formEmailSubmit() ) {
                valEmail.addClass("invalid");
                return false;
            } else if ( !formCaptchaSubmit() ) {
                valCaptcha.parent().addClass("invalid");
                return false;
            } else if ( !formNameSubmit() ) {
                valName.addClass("invalid");
                    return false;
                } else if ( !formMessageSubmit() ) {
                    valMsg.addClass("invalid");
                    return false;
                } else {
                    return false;
                }
            }
        });
    });
    // END VALIDATION
    /////////////////
});