title: JS/jQuery TypeError: jQuery(...).datepicker is not a function
body: <p>I've been scratching my head on this for 2 days, pretty sure I'm just missing something simple but I can't for the life of me figure out why it's not working.</p>
  
  <p>I'm trying to use the script below on my WordPress site to disable specific dates within a datepicker field in a ContactForm7 form.</p>
  
  <p>I can load the script in jsfiddle with a simple input field using the same id and it works perfectly...but when I add it to my site the dates aren't disabled, and there's an error in the JS error console that says "jQuery(...).datepicker is not a function"</p>
  
  <p>I've added it in my <code>header.php</code> file, just below the <code>wp_head()</code> call and just above the <code>&lt;/head&gt;</code> tag. I've assigned my datepicker field with the id of <code>dpick</code> like the script uses.</p>
  
  <p>I read that this error is commonly caused when using the <code>$</code> symbol because it can conflict with other jQuery scripts within WordPress...so they suggested replacing <code>$</code> with <code>jQuery</code> instead (which I've done in the script below)...but I'm still getting the error</p>
  
  <pre><code>var unavailableDates = ["1-9-2013", "2-9-2013", "3-9-2013", "4-9-2013", "5-9-2013"];
  
      function unavailable(date) {
              dmy = date.getDate() + "-" + (date.getMonth() + 1) + "-" + date.getFullYear();
              if (jQuery.inArray(dmy, unavailableDates) == -1) {
                  return [true, ""];
              } else {
                  return [false, "", "Unavailable"];
          }
      }
  
          jQuery(function() {
              jQuery( '#dpick' ).datepicker({
                  dateFormat: 'dd MM yy',
                  beforeShowDay: unavailable
          });
  
      });
  </code></pre>
  
  <p>Can't thank you enough for any help you can offer...this seems like such a simple thing but I just can't seem to wrap my head around it!</p>