title: Uncaught TypeError: Cannot read property 'ajax' of undefined When I'm trying to send data to url
body: <p>I have created a form to get feedback from user, I’m simply trying to send form data to url, but I’m getting this error:</p>
  
  <blockquote>
    <p>Uncaught TypeError: Cannot read property 'ajax' of undefined</p>
  </blockquote>
  
  <pre><code>function sendData(){
      $.ajax({
          url: "www.yashkjhsah.php",
          type: "POST",
          async: true,
          data: $(".contacts_form").serialize(),
          dataType: "html",
          success: function(data) 
          {
              alert(data);
              if(data!="Error in Insert Query!")
              {
                  alert("Thank you for Enquiry we will send answer in your Mail.");
              }
              else
              {
                  alert("Error while saving the data");
              }
          }
      });
  }
  </code></pre>