Form Validator

function solve() {
    return function(){
        let userRegex = /^[a-zA-Z0-9]{3,20}$/;
        let passwordRegex = /^[a-zA-Z0-9_]{5,15}$/;
        let emailRegex = /(@)([ -~]+)(\.)/;
        let companyShitReg = /\b[1-9][1-9][1-9][1-9]\b/;
        $("#registerForm").submit(function(e) {
            e.preventDefault();
        });
        $('input#company').click(function () {
            if($('#company').attr('checked','checked')){
                $('#companyInfo').attr('style','display-inline');
            }
            if($('#company').not(':checked').length){
                $('#companyInfo').attr('style','display:none');
            }
        });
        $('#submit').click(function () {
            let counter = 0;
            let username = $('input#username').val();
            let password = $('input#password').val();
            let confirmPassword = $('input#confirm-password').val();
            let email = $('input#email').val();
            let compNumber = $('input#companyNumber').val();
            if(password != confirmPassword){
                $('input#confirm-password').attr('style','border-color: red;');
                $('input#password').attr('style','border-color: red;');
                counter++;
            }
            else {
                $('input#confirm-password').removeAttr('style');
                $('input#password').removeAttr('style');
                counter = 0;
            }
            if(!username.match(userRegex)){$('input#username').attr('style','border-color: red;');}
            else {$('input#username').removeAttr('style');}
            if(!password.match(passwordRegex)){$('input#password').attr('style','border-color: red;')}
            else {
                if(counter == 0) {
                    $('input#password').removeAttr('style');
                }
            }
            if(!confirmPassword.match(passwordRegex)){$('input#confirm-password').attr('style','border-color: red;');}
            else {
                if(counter == 0) {
                    $('input#confirm-password').removeAttr('style');
                }
            }
            if(!email.match(emailRegex)){$('input#email').attr('style','border-color: red;');}
            else {$('input#email').removeAttr('style');}
            if($('#company').is(':checked')){
                if(!compNumber.match(companyShitReg)){$('input#companyNumber').attr('style','border-color: red;');}
                else{$('input#companyNumber').removeAttr('style');}
            }
            if(!$('input#confirm-password').is('[style]')
                && !$('input#username').is('[style]')
                && !$('input#password').is('[style]')
                && !$('input#email').is('[style]')
                && !$('input#companyNumber').is('[style]'))$('#valid').attr('style','display-inline');
            else $('#valid').attr('style','display:none');
        })
    }
}