title: How to induce a spreadsheet's onFormSubmit trigger in script?
body: <p>Is there a way to trigger a spreadsheet’s onFormSubmit  in script? That is, instead of using a google form to trigger onFormSubmit?
  I attempted the below sendHttpPost code posting to a spreadsheet Web App: </p>
  
  <pre><code>function sendHttpPostSelf() {
  var payload = {
        "name" : "name",
        "comment" : "comment",
      };
    var options = {
        "method" : "post",
        "payload" : payload
      };
  var url="https://script.google.com/macros/s/AKfycbzlVoiDQMbLe4yliErDoNub6A0m3tijSfPAUMEBENgIikQnLQ_H/exec";
  var resp=UrlFetchApp.fetch(url,options);
  Logger.log(resp.getContentText());
  } 
  </code></pre>
  
  <p>The code correctly triggers doPost() in the spreadsheet Web App. But, the code does not trigger the spreadsheet’s onFormSubmit. Alternately, is there any way to script an <em>onInsert</em> trigger when inserting into a spreadsheet?</p>