JSFiddle - React, Tailwind, and code Playground

HTML

<div id="Sign-In">
    <fieldset style="width:30%">
        <legend>LOG-IN HERE</legend>
        <form id="form1" method="POST" action="connectivity.php">User
            <br/>
            <input type="text" name="user" size="40" />
            <br/>Password
            <br/>
            <input type="password" name="pass" size="40" />
            <br/>
            <input id="button" type="submit" name="submit" value="Log-In"/>
        </form>
    </fieldset>
</div>

JavaScript

$("#form1").submit(function(e){
    e.preventDefault();
    $.ajax({
        url:'connectivity.php',
        method:'POST',
        success:function(rs){
            if( rs == "success" )
               window.location.href("logout_success.php");
        },
        error:function(){
            alert("Error");
        }
    });
    return false;
});