Checking values against an array to prevent data duplication

array.gs

function myFunction() {
  var sheet = SpreadsheetApp.getActiveSpreadsheet().getActiveSheet(); 
  var lastRow = sheet.getLastRow()
  var employees = [];

  for ( var i = 0; i < lastRow; i++) {
    let value = sheet.getRange(i+1,1).getValue(); 
    employees.push(value);
  };

  Logger.log(employees);

}

Code.gs

function myFunction() {
  var sheet = SpreadsheetApp.getActiveSpreadsheet().getActiveSheet(); 
  var nameArray = ["Eddie", "Jaime", "Katie", 42];

  var inputFromUser = Browser.inputBox('Please enter a value');

  Logger.log(inputFromUser);  

  let checkCell = sheet.getRange("A1");

  if ( nameArray.indexOf(inputFromUser) >= 0) {
    checkCell.setValue("That value is in the array");
  } else {
    checkCell.setValue("That value is NOT in the array");
    checkCell.setBackground("red"); 
  }; 
};