Jak spustit JavaScript validaci formuláře v php souboru

<div id="page">
  
<?php
    include ("_rsrc/_menu.php");    
    include ("_rsrc/_box.php");    
   ?>  
        <div id="content">
                            <h1 class="title">Nezávazná objednávka</h1>
<?php 
echo '<script src="_js/form_validation.js" type="text/javascript"></script>';
?>        
<form  name="myForm" method="POST" action="_rsrc/zpracuj.php" onsubmit="return validateForm()" >
<h3>Jak vás budeme kontaktovat</h3>
  <label  class="left" for="item1">Jméno:<font color="red">*</font></label><input id="item1" name="fname" ><br>
  <label  class="left" for="item2">Telefon:<font color="red">*</font></label><input id="item2" name="ftelephone"><br>
  <label  class="left" for="item3">email:<font color="red">*</font></label><input id="item3" name="femail" value="@"><br><br>
<label  class="left" for="item17"><input type="Submit" nvalue="Submit"></label><br> 
</form><br>
<span class="poznamka">* tento formuář je nezávazný a má pouze informační charakter!<span><br>
            </div>
        </div>
<?php
    include ("_rsrc/_footer.php");
?>

<script type="text/javascript">
function validateForm()
{
var x=document.forms["myForm"]["fname"].value;
if (x==null || x=="")
  {
  alert("Name must be filled out");
  return false;
  }
  var x=document.forms["myForm"]["ftelephone"].value;
if (x==null || x=="")
  {
  alert("Telephone must be filled out");
  return false;
  }
  var x=document.forms["myForm"]["femail"].value;
if (x==null || x=="")
  {
  alert("email must be filled out");
  return false;
  }
}
</script>