Don't add data if its already in google sheet

Currently I have parameters being added to my google sheet on page load.

The URL looks like https://example.com/page?Name=John&Email=john@gmail.com

I'm wondering how I can stop this data being added a second time if people visit this URL again.

I currently stop a resubmission on page reload, but this doesn't stop a user if the URL is placed in a new tab, or opened on another device.

Is there a way to check if the same parameters are already in the sheet, and stop it being added if it is.

Javascript:

if (performance.navigation.type != performance.navigation.TYPE_RELOAD) {
const queryParameters = Object.fromEntries(new URLSearchParams(window.location.search));
const scriptURL = 'https://script.google.com/macros/s/script/exec';
const data = new FormData();
Object.entries(queryParameters).forEach(e => data.append(...e));
fetch(scriptURL, { method: 'POST', body: data })
.then(response => console.log('Success!', response))
.catch(error => console.error('Error!', error.message))
}

Google Script

var sheetName = 'Sheet1'
var scriptProp = PropertiesService.getScriptProperties()
function intialSetup () {
var activeSpreadsheet = SpreadsheetApp.getActiveSpreadsheet()
scriptProp.setProperty('key', activeSpreadsheet.getId())
}
function doPost (e) {
const { Name, Email, sample } = e.parameter;
if (sample == "delete") {
var sheet = SpreadsheetApp.getActiveSpreadsheet().getSheetByName(sheetName);
var ranges = sheet.getDataRange();
var values = ranges.getValues().filter(r => ![Name, Email].every(e => r.includes(e)));
if (ranges.length == 0) {
return ContentService.createTextOutput(`"${email}" was not found.`);
}
ranges.clearContent().offset(0, 0, values.length, values[0].length).setValues(values);
return ContentService.createTextOutput(`Rows including "${Email}" were deleted.`);
}
var lock = LockService.getScriptLock()
lock.tryLock(10000)
try {
var doc = SpreadsheetApp.openById(scriptProp.getProperty('key'))
var sheet = doc.getSheetByName(sheetName)
var headers = sheet.getRange(1, 1, 1, sheet.getLastColumn()).getValues()[0]
var nextRow = sheet.getLastRow() + 1
var newRow = headers.map(function(header) {
return header === 'Timestamp' ? 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()
}
}

I hope that makes sense, I am happy to clarify.

Thank you.

In your script, how about the following modification?

From:

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

To:

try {
var doc = SpreadsheetApp.openById(scriptProp.getProperty('key'))
var sheet = doc.getSheetByName(sheetName)
var values = sheet.getDataRange().getValues().filter(r => [Name, Email].every(e => r.includes(e)));
if (values.length > 0) {
return ContentService.createTextOutput("Values were not appended.");
}

• By this modification, when the values of Name and Email are existing, the script is stopped.

Note:

• When you modified the Google Apps Script of Web Apps, please modify the deployment as a new version. By this, the modified script is reflected in Web Apps. Please be careful about this.

• You can see the detail of this in my report "Redeploying Web Apps without Changing URL of Web Apps for new IDE (Author: me)".

References:

• filter()
• every()