opacity?

$(document).ready(function () {

    var authListErrors = [];

    var alnum = /^[a-z0-9]*$/;

    var authErrorsObject = {
        "mail_emptyField": "Your mailbox really needs a name",
        "mail_alnumField": "Your name can only made out of letters and numb3rz",
        "pass_emptyField": "Empty password is not most secure",
        "pass_insecField": "Password is too short, 6 characters at least"
    };

    var preventLogin = true;

    var fldAuthMail = $(".authTextFields").eq(0);
    var fldAuthPass = $(".authTextFields").eq(1);

    var objAuthErrorSpan = $("#loginError");

    objAuthErrorSpan.css('opacity', 0);

    function AuthErrorManager( listArray, contextFlag, isError ) {

        if (listArray.indexOf( contextFlag ) === -1 && isError) {
            listArray.push( contextFlag );
        } else if (listArray.indexOf( contextFlag ) !== 1 && !isError) {
            i = listArray.indexOf( contextFlag );
            listArray.splice(i, 1);
        }

    }

    function outputErrors( errorObject, listArray, glue){
        var retStr = '';
        if( listArray.length ){
            $.each( listArray, function( i, v ){
                if( retStr ) retStr += glue;
                retStr += errorObject[v];
            });
        }
        return retStr;
    }

    function changeClasses( jQueryInputElement, jQueryErrorElement, listArray, okClassName, errClassName ){

        //PROBLEM
        if( listArray.length ){
            if( !jQueryInputElement.hasClass( errClassName ) ) doErrTransition( jQueryErrorElement );
            jQueryInputElement.addClass( errClassName );
            jQueryInputElement.removeClass( okClassName );

        }else{
            if( !jQueryInputElement.hasClass( okClassName ) ) doOkTransition( jQueryErrorElement );
            jQueryInputElement.addClass( okClassName );
            jQueryInputElement.removeClass( errClassName );

        }
    }

    function checkSubmit( arrayListArrays ){
        $.each( arrayListArrays, function(i, v){
            if( v.length ) {
                return true;
            }
        });
        return false;
    }

    function doErrTransition( element ){
        element.animate({"opacity": 1});
    }

    function doOkTransition( element ){
        element.animate( {"opacity": 0}, function () {
            element.empty();
        });
    }


    fldAuthMail.focusout(function () {
        var boolEmpty = ($(this).val().trim() === '') ? true : false;
        var boolNotAlnum = (alnum.test($(this).val())) ? false : true;

        AuthErrorManager( authListErrors, "mail_emptyField", boolEmpty );
        AuthErrorManager( authListErrors, "mail_alnumField", boolNotAlnum );

        objAuthErrorSpan.html( outputErrors( authErrorsObject, authListErrors, '<br>') );
        changeClasses( fldAuthMail, objAuthErrorSpan, authListErrors, "correctInput", "incorrectInput" );
        preventLogin = checkSubmit(  [authListErrors] );

    });

    fldAuthPass.focusout(function () {
        var boolEmpty = ($(this).val().trim() === '') ? true : false;
        var boolLength = ($(this).val().length < 6) ? true : false;

        AuthErrorManager( authListErrors, "pass_emptyField", boolEmpty );
        AuthErrorManager( authListErrors, "pass_insecField", boolLength );

        objAuthErrorSpan.html( outputErrors( authErrorsObject, authListErrors, '<br>') );
        changeClasses( fldAuthPass, objAuthErrorSpan, authListErrors, "correctInput", "incorrectInput" );
        preventLogin = checkSubmit(  [authListErrors] );

    });

});