How to create a login form using Google Apps Script with Google Sheets as the backend

To create a login form using Google Apps Script with Google Sheets as the backend, follow these steps:

Step 1: Open a new or existing Google Sheets document.

Step 2: Go to "Extensions" > "Apps Script" to open the Google Apps Script editor.

Step 3: In the script editor, delete any existing code and replace it with the following code:

```javascript

function onOpen() {

var ui = SpreadsheetApp.getUi();

ui.createMenu('Login')

.addItem('Show Login Form', 'showLoginForm')

.addToUi();

}

function showLoginForm() {

var htmlOutput = HtmlService.createHtmlOutputFromFile('login')

.setWidth(300)

.setHeight(200);

SpreadsheetApp.getUi().showModalDialog(htmlOutput, 'Login');

}

function processLogin(username, password) {

var sheet = SpreadsheetApp.getActiveSpreadsheet().getActiveSheet();

var dataRange = sheet.getDataRange();

var values = dataRange.getValues();

for (var i = 1; i < values.length; i++) {

var storedUsername = values[i][0];

var storedPassword = values[i][1];

if (username === storedUsername && password === storedPassword) {

      SpreadsheetApp.getUi().alert('Login successful!');

      return;

    }

  }

  

  SpreadsheetApp.getUi().alert('Invalid username or password. Please try again.');

}

```

Step 4: In the script editor, click on "File" > "New" > "Html file" to create a new HTML file.

Step 5: Replace the default code in the HTML file with the following code for the login form:

```html

 

   

   

 

 

   

      Username:

     

   

   

      Password:

     

   

   

   

 

```

Step 6: Save the script by clicking on the floppy disk icon or pressing `Ctrl + S`.

Step 7: Close the script editor.

Step 8: In the Google Sheets document, go to "Extensions" > "Apps Script" > "Login" > "Show Login Form" to display the login form.

The code above creates a custom menu item in Google Sheets called "Login" and adds an option to show the login form. When the login form is displayed, users can enter their username and password. The `processLogin` function in the script is called when the "Login" button is clicked. It compares the entered credentials with the data stored in the active sheet of the Google Sheets document and displays an alert indicating whether the login was successful or not.

Note: Ensure that your Google Sheets document has a sheet with the login data, where the usernames are stored in the first column and the corresponding passwords are stored in the second column.