I have made a custom function on Google Sheets that allows the user to see how much they have spent on an expense.

Here is the example output:

The HTML sidebar:

Here is the JavaScript function:

function perCentBrand(brand){
  var sh = SpreadsheetApp.getActiveSpreadsheet().getActiveSheet();
  var values = sh.getRange(2,1,sh.getLastRow()-1,sh.getLastColumn()).getValues();
  var total = 0;
  var sum = 0;
  values.forEach(function(row){
    total+=row[1];
    if (row[6]==brand){sum+=row[1]}
  })
  var val = "You spent a total of " + sum + " on " + brand + " out of " + total + " ." + " Additionally, " + (sum/total)*100 + "%"  + " of your income has been spent on " + brand; 
  var ui = SpreadsheetApp.getUi();
  ui.alert(val)
}

And here is the HTML form code:

    <form onsubmit="runFunc()">
      <input class = "u-full-width " id="brand" type = "text" placeholder="Enter brand name">

    <div class="u-full-width" style="display:flex; justify-content: center">
      <button type="submit" class="button-primary">Submit</button>
    </div>
    </form>

I have read about the toLowerCase() and the toUpperCase() methods but I am unsure if these should be included to make the user input case insensitive.

Thanks in advance.