Validating my PHP-based form does not work in recent versions of IE, Firefox, or Opera. I click the submit button with empty values ​​in my form fields to initiate validation, but the page just refreshes.

The odd thing is that check messages and errors work in Chrome and Safari.

Take a look here: http://www.directsponsor.org/contact/

Can someone advise me on known issues regarding why PHP might not work in certain browsers, some browsers behave differently?

Sorry for the mountains of code in advance, although I assume this is necessary:

Here is the form:

    <form method="post" action="http://www.directsponsor.org/contact/">
  <fieldset>
  <ul>
  <?php if(isset($_POST['contactsubmit'])){
  if (!$contactnamevalidation){
  echo "<li class='contactfail'><p><img src='"; echo bloginfo('stylesheet_directory'); echo "/images/icons/101-large.png'>&nbsp;&nbsp;&nbsp;You did not input your <strong>name</strong>.</p></li>";
  }
  }
  ?>
  <li>
    <label for="contactname">Your name <em>(required)</em></label> 
    <input type="text" name="contactname" class="textbox" value="<?php if (isset($_POST['contactname'])) {echo htmlspecialchars($_POST['contactname'], ENT_QUOTES);    }?>">
 </li>
 <?php if(isset($_POST['contactsubmit'])){
  if (!$contactemailvalidation1){
  echo "<li class='contactfail'><p><img src='"; echo bloginfo('stylesheet_directory'); echo "/images/icons/101-large.png'>&nbsp;&nbsp;&nbsp;You did not input your <strong>email</strong>.</p></li>";
  }
  }
  ?>
 <?php if(isset($_POST['contactsubmit'])){
  if (!$contactemailvalidation2){
  echo "<li class='contactfail'><p><img src='"; echo bloginfo('stylesheet_directory'); echo "/images/icons/101-large.png'>&nbsp;&nbsp;&nbsp;You did not input a <strong>valid email</strong>.</p></li>";
  }
  }
  ?>
  <li>
    <label for="contactemail">Your email <em>(required)</em></label>
    <input type="text" name="contactemail" class="textbox" value="<?php if (isset($_POST['contactemail'])) {echo htmlspecialchars($_POST['contactemail'], ENT_QUOTES);    }?>">
 </li>
 <?php if(isset($_POST['contactsubmit'])){
  if (!$contactmessagevalidation){
  echo "<li class='contactfail'><p><img src='"; echo bloginfo('stylesheet_directory'); echo "/images/icons/101-large.png'>&nbsp;&nbsp;&nbsp;You did not input a <strong>message</strong>.</p></li>";
  }
  }
  ?>
  <li>
    <label for="contactmessage">Message <em>(required)</em></label>
    <textarea name="contactmessage"><?php if (isset($_POST['contactmessage'])) {echo htmlspecialchars($_POST['contactmessage'], ENT_QUOTES);    }?></textarea>
  </li>
  <li class="buttons">
  <label for="contactsubmit">&nbsp;</label><input type="image" src="/wp-content/themes/directsponsor/images/button-sendmessage.png" name="contactsubmit" value="Submit Message">

  <?php if(isset($_POST['contactsubmit'])){echo"<a href='http://www.directsponsor.org/contact/'><img src='/wp-content/themes/directsponsor/images/button-clearform.png'/></a>";} ?>
  </li>
  </ul>
  </fieldset>
  </form>

Here (important part) of the check:

    <?php 
if(isset($_POST['contactsubmit'])){

// Check here.

}
?>

Answer

, IE, FireFox Opera , -, Chrome Safari.

:

if(isset($_POST['contactsubmit'])){

IE, Firefox Opera :

//Values for image as a submit button.
contactsubmit_x
contactsubmit_y

contactsubmit, if(isset()) . , , , , :

if(isset($_POST['contactemail'])){

, contactemail.