Untitled

function doGet(e){
  // code make changes to spreadsheet

 // here I want browser window to close

  return HtmlService.createHtmlOutput(uniqueid + " is marked complete");
};

<script>
  window.top.close();
</script>

<script>
  setTimeout(function(){ window.top.close(); }, 3000);
</script>

<script>
  window.onload=function(){
    console.log("This onload did run");
    setTimeout(function(){ window.top.close(); }, 3000);
  };
</script>

<!DOCTYPE html>
<html>
    <script>
        window.top.close();
    </script>
</html>

function doGet(e){
  // code make changes to spreadsheet
  var ss = SpreadsheetApp.openById([The key for the spreadsheet you wish you modify])
  var sheet = ss.getActiveSheet()
  var lastRow = sheet.getLastRow()
  var params = JSON.stringify(e);
  var paramsArray = JSON.parse(params)
  sheet.getRange(lastRow + 1, 1).setValue('Code made changes to spreadsheet at ' + Date())
  sheet.getRange(lastRow + 1, 2).setValue(paramsArray.parameter.change)

  // here I want browser window to close
  var uniqueid = "Someuniqueid"
  return HtmlService.createHtmlOutputFromFile('Close Window'), HtmlService.createHtmlOutput(uniqueid + " is marked complete")
};

function mailIt() {
var emailAddress = Browser.inputBox('What email address do you want to send the WebApp to?')
var html = HtmlService.createTemplateFromFile('HTML Email to run Web App')
var htmlCode = html.getRawContent()
Logger.log(htmlCode)
  MailApp.sendEmail({
    name: "Publish WebApp for survey embed Test",
    to: emailAddress,
    subject: "Publish WebApp for survey embed Test",
    htmlBody:  htmlCode
  })
}

<!DOCTYPE html>
<html>
  <form action=[Your current Web App URL in quotes]>
  Send text to spreadsheet: <input type="text" name="change"><br>
  <input type="submit" value="Submit">
  </form>
</html>

google.script.host.close();