HTML Form Submission to Google Sheets using Apps Scripts Landing "Thank You" Page

Question

I have setup a Google Apps Script as a WebApp to take form data from an HTML form (non-google form) and insert the results into Google Sheets. Everything is working, but I am trying to get a custom landing page instead of the current Apps Script page, which is not useful for the end user.

I used this for reference: https://github.com/levinunnink/html-form-to-google-sheet

There is some info at the end of this GitHub guide, but it is not descriptive and I cannot find anything that works here or on GitHub. I know some JS, but I am no expert and could really use a hand figuring this out. Below is what I have and this is the closest I have gotten to everything working.

Here is my HTML.

<script>
function myFunction()
{ alert("The form was submitted successfully. Please press okay to continue...");
window.open("URL-to-thanks-page", "_top");
}
</script>

<form class="googleform" name="googleform" id="googleform" target="_top" method="POST" onsubmit="myFunction()" action="MY-GOOGLE-APPS-SCRIPTS-URL">
        <!--FORM STUFF-->
    <button type="submit" class="btn-default btn" name="submit" access="false" style="default" id="submit">Submit</button>
</form>

Here is my Code.gs

const sheetName = 'RSVP'
const scriptProp = PropertiesService.getScriptProperties()

function intialSetup () {
  const activeSpreadsheet = SpreadsheetApp.getActiveSpreadsheet()
  scriptProp.setProperty('key', activeSpreadsheet.getId())
}

function doPost (e) {
  const lock = LockService.getScriptLock()
  lock.tryLock(10000)

  try {
    const doc = SpreadsheetApp.openById(scriptProp.getProperty('key'))
    const sheet = doc.getSheetByName(sheetName)

    const headers = sheet.getRange(1, 1, 1, sheet.getLastColumn()).getValues()[0]
    const nextRow = sheet.getLastRow() + 1

    const newRow = headers.map(function(header) {
      return header === 'Date' ? new Date() : e.parameter[header]
    })

    sheet.getRange(nextRow, 1, 1, newRow.length).setValues([newRow])

    return ContentService
      .createTextOutput(JSON.stringify({ 'result': 'success', 'row': nextRow }))
      .setMimeType(ContentService.MimeType.JSON)
  }

  catch (e) {
    return ContentService
      .createTextOutput(JSON.stringify({ 'result': 'error', 'error': e }))
      .setMimeType(ContentService.MimeType.JSON)
  }

  finally {
    lock.releaseLock()
  }
}

Any help would be greatly appreciated.

Respectfully,

Answer 1

I figured this out actually. I used the code on the original guide with a modification. In my HTML I removed the previous <script> section and changed it to the following:

<script>
window.addEventListener("load", function() {
  const form = document.getElementById('googleform');
  form.addEventListener("submit", function(e) {
    e.preventDefault();
    const data = new FormData(form);
    const action = e.target.action;
    fetch(action, {
      method: 'POST',
      body: data,
    })
    .then(() => {
    window.location.href = 'URL of thank you page';
    })
  });
});
</script>

This fixed the issue and now everything is working correctly.