title: How to show a success dialog box after submitting the form in html?
body: <p>I'm a newbie to php and html, I've created a form which will accept the inputs from user and will send it to a specified Email id. Everything is working fine but on submitting the form, it goes to another new page. 
  How this can be replaced with a dialog box as a confirmation message upon submitting the form?</p>
  
  <p>HTML -</p>
  
  <pre><code>&lt;form method="POST" name="contactform" action="contact-form-handler.php"&gt; 
  &lt;p&gt;
  &lt;label for='name'&gt;Your Name:&lt;/label&gt; &lt;br&gt;
  &lt;input type="text" name="name"&gt;
  &lt;/p&gt;
  &lt;p&gt;
  &lt;label for='email'&gt;Email Address:&lt;/label&gt; &lt;br&gt;
  &lt;input type="text" name="email"&gt; &lt;br&gt;
  &lt;/p&gt;
  &lt;p&gt;
  &lt;label for='message'&gt;Message:&lt;/label&gt; &lt;br&gt;
  &lt;textarea name="message"&gt;&lt;/textarea&gt;
  &lt;/p&gt;
  &lt;input type="submit" value="Submit"&gt;&lt;br&gt;
  &lt;/form&gt;
  </code></pre>
  
  <p>PHP -</p>
  
  <pre><code>&lt;?php 
  $errors = '';
  $myemail = 'mymail@gmail.com';//&lt;-----Put Your email address here.
  if(empty($_POST['name'])  || 
     empty($_POST['email']) || 
     empty($_POST['message']))
  {
      $errors .= "\n Error: all fields are required";
  }
  
  $name = $_POST['name']; 
  $email_address = $_POST['email']; 
  $message = $_POST['message']; 
  
  if (!preg_match(
  "/^[_a-z0-9-]+(\.[_a-z0-9-]+)*@[a-z0-9-]+(\.[a-z0-9-]+)*(\.[a-z]{2,3})$/i", 
  $email_address))
  {
      $errors .= "\n Error: Invalid email address";
  }
  
  if( empty($errors))
  {
      $to = $myemail; 
      $email_subject = "Contact form submission: $name";
      $email_body = "You have received a new message. ".
      " Here are the details:\n Name : $name \n Email : $email_address \n Message : $message"; 
  
      $headers = "From: $myemail\n"; 
      $headers .= "Reply-To: $email_address";
  
      mail($to,$email_subject,$email_body,$headers);
      //redirect to the 'thank you' page
      echo "Your Message successfully sent, we will get back to you ASAP.";
  } 
  ?&gt;
  &lt;!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"&gt; 
  &lt;html&gt;
  &lt;head&gt;
      &lt;title&gt;Contact form handler&lt;/title&gt;
  &lt;/head&gt;
  
  &lt;body&gt;
  &lt;!-- This page is displayed only if there is some error --&gt;
  &lt;?php
  echo nl2br($errors);
  ?&gt;
  
  
  &lt;/body&gt;
  &lt;/html&gt;
  </code></pre>