JSFiddle - React, Tailwind, and code Playground

HTML

<h2>Регистрация</h2>

<form action="javascript:alert( 'success!' );" id="form">
    <label for="fname">First Name</label>
    <input type="text" id="fname" required>
        
    <label for="lname">Last Name</label>
    <input type="text" id="lname" required>
    
    <label for="birthdate">Birth Date</label>
    <input type="date" id='birthdate' required>
    
    <label for="email">Email</label>
    <input type="email" id="email" required>
    
    <label for="pass">Pass</label>
    <input type="password" id="pass" required>
    
    <label for="pass_r">Pass</label>
    <input type="password" id="pass_r" required>

    <input type="submit">
</form>

CSS

label{
    display: block;
}

input{
    display: block;
    margin: 15px 5px;
}

JavaScript

(function(){
    var form = $('#form');
    
    form.on('submit', function(event){
        var pass = $('#pass').val();
        var pass_r = $('#pass_r').val();
        if( pass !== pass_r ){
            alert('password!');
        }
        event.preventDefault();
        return;
    });
})();