JSFiddle - React, Tailwind, and code Playground

HTML

<div id="signup">
    <form  id="suform" method="POST" action="signup/newUser">
        <p>
            <label>Frist Name</label>
            <input type="text" name="fName"/>
            <span class="errorMessage"></span>
        </p>
        <p>
            <label>Last Name</label>
            <input type="text" name="lName"/>
            <span class="errorMessage"></span>
        </p>
        <p>
            <label>Email</label>
            <input type="text" name="Email"/>
            <span class="errorMessage"></span>
        </p>
        <p>
            <label>Mobile Number</label>
            <input type="text" name="MNumber"/>
            <span class="errorMessage"></span>
        </p>
        <p>
            <label>Password</label>
            <input type="password" name="Password" id="Password" />
            <span class="errorMessage"></span>
        </p>
        <p>
            <label>Re Password</label>
            <input type="password" name="RePassword" id="RePassword" />
            <span class="errorMessage"></span>
        </p>
        <p>
            <input type="submit" class="button" value="sign up"/>
        </p>
    </form>
</div>

JavaScript

$(document).ready(function(){
    $('#suform').on('submit', function(e){
        e.preventDefault();
        var errorCount = 0;
        $('span.errorMessage').text(''); // reset all error mesaage
        $('input').each(function(){
            
            var $this = $(this);
            
            if($this.val() === ''){
                var error = 'Please fill ' + $this.prev('label').text(); // take the input field from label
                $this.next('span').text(error);
                errorCount = errorCount + 1;   
            }else if($this.attr('id') === 'Password'){
                //compare the two fields
                if($('#Password').val() !== $('#RePassword')){
                    //they don't match, do stuff
                    
                }
            }
            
        });
        if(errorCount === 0){
            $(this)[0].submit(); // submit form if no error
        }
    });
    
});