By following the instruction of this website, I made a web app using Google App Script (GAS) which will display the search when a user enters a search term (e.g. order number, status, price) in the search window and the search is successful (The screenshot below represents what I expected). However, my app always returns 'Data not found!' even if the search term exists in the data. What am I missing, then?

Components of the app

Data

A spreadsheet that contains the exactly same contents of the original spreadsheet (i.e. I copied the original contents and pasted them to my own spreadsheet to prepare the data)

Index.html

I copied the code from https://gist.github.com/bpwebs/dbbd96f8262e486c8f4c321ea0d3a95a#file-index-html and pasted it to 'Index.html' in my own GAS project.

Code.gs

I modified the original code on https://gist.github.com/bpwebs/dbbd96f8262e486c8f4c321ea0d3a95a#file-code-gs since the original code has an undefined variable (Sheets on ln.19) and cannot open the spreadsheet. I replaced the relevant code with SpreadsheetApp.openById() and range.getValues().

function doGet() {
  return HtmlService.createTemplateFromFile('Index').evaluate();
}
 
 
/* PROCESS FORM */
function processForm(formObject){  
  var result = "";
  if(formObject.searchtext){//Execute if form passes search text
      result = search(formObject.searchtext);
  }
  return result;
}
 
//SEARCH FOR MATCHED CONTENTS 
function search(searchtext){
  // var spreadsheetId   = '1p7fKVM7HA4Ikl8gYC2WesmHcIqAqJQWTfIuiqB4SyN4'; //** CHANGE !!!
  // var dataRage        = 'Data!A2:Y';                                    //** CHANGE !!!
  var ss = SpreadsheetApp.openById('The URL to my spreadsheet');
  var range = ss.getRange('Data!A2:Y');
  var data = range.getValues();
  // var data = Sheets.Spreadsheets.Values.get(spreadsheetId, dataRage).values;
  var ar = [];
   
  data.forEach(function(f) {
    if (~f.indexOf(searchtext)) {
      ar.push(f);
    }
  });
  return ar;
}