php与js互相调用

php中调用js

 <?php
 echo '<script>var yearid=$("#yearId").val()</script>';
 echo $yearid='<script>document.write(yearid);</script>';
 ?>

js中调用php

 <?php
 $userId=100;
 ?>
  <script>
 var userId;
 userId=$("#userId").value;
 alert (userId);
 </script>
 <input type="text" name="userId" id="userId" value="<?php echo $userId; ?>">