function validate() {
	// TODO:

    $('#submit').on('click',validateForm);

    let companyChecked = $("#company").on("change", function () {
        if ($(this).is(":checked")) {
            $('#companyInfo').css('display', 'block');
        } else {
            $('#companyInfo').css('display', 'none');
        }
    });

    function validateForm(event) {
        event.preventDefault();
        let usernamePattern = /^[A-Za-z\d]{3,20}$/;
        let passwordPattern = /^\w{5,15}$/;
        let emailPattern = /^.*@.*\..*$/;
        let companyInfoPatten = /^\d{4}$/;

        let username = $("#username");
        let password = $("#password");
        let confirmPassword = $("#confirm-password");
        let email = $("#email");

        let areAllValid = true;

        if(usernamePattern.test(username.val())===false){
            areAllValid=false;
            username.attr("style",'border-color: red');
        }
        if(passwordPattern.test(password.val())===false) {
            areAllValid=false;
            password.attr("style",'border-color: red');
        }
        if(confirmPassword.val()!==password.val()||passwordPattern.test(confirmPassword.val())===false){
            areAllValid=false;
           confirmPassword.attr("style",'border-color: red');
        }
        if (emailPattern.test(email.val())===false){
            areAllValid=false;
            email.attr("style",'border-color: red');
        }

        let companyIsChecked = $('#company').is(':checked');

        if (companyIsChecked === true) {
           let companyInfo=$("#companyNumber");

           if(companyInfoPatten.test(companyInfo.val())===false){
               areAllValid=false;
               companyInfo.attr("style",'border-color: red');
           }

        }

        if(areAllValid){
            $("#valid").attr("style","display: visible");
        }
    }

}