title: Adding parameters to XMLHttpRequests causes 405 Error
body: <p>I can successfully send an XMLHttpRequest without parameters using this code:</p>
  
  <p>template file:</p>
  
  <pre><code>xhr.open('POST', '/mytemplate');
  xhr.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
  xhr.onload = function() {
     if (xhr.status == 200) {
        alert('success');
     }
     else {
        alert('failed:' + xhr.status);
     }
  }
  xhr.send();
  </code></pre>
  
  <p>router:</p>
  
  <pre><code>r.HandleFunc("/mytemplate", MyHandler).Methods("POST")
  </code></pre>
  
  <p>But as soon as I try to add parameters I get a 405 error. I only change 2 lines, not sure what I am doing wrong:</p>
  
  <p>template file:</p>
  
  <pre><code>xhr.open('POST', '/mytemplate?param1='+var1+'&amp;param2='+var2+'&amp;param3='+var3);
  </code></pre>
  
  <p>router:</p>
  
  <pre><code>r.HandleFunc("/mytemplate/{param1}/{param2}/{param2}", MyHandler).Methods("POST")
  </code></pre>