var mainWsName = ["Car", "Dota"];
var optionsWsName = {Car: "Car_L", Dota: "Heroes"};
var firstLevelColumn = 1;
var secondLevelColumn = 2;
var thirdLevelColumn = 3;
var ws;// = SpreadsheetApp.getActiveSpreadsheet().getSheetByName(mainWsName);
var wsOptions;// = SpreadsheetApp.getActiveSpreadsheet().getSheetByName(optionsWsName);
var options;// = wsOptions.getRange(1, 1, wsOptions.getLastRow(),3).getValues();

function onEdit(e) {
  var activeCell = e.range;
  var val = activeCell.getValue();
  var r = activeCell.getRow();
  var c = activeCell.getColumn();
  var wsName = activeCell.getSheet().getName();
  ws = SpreadsheetApp.getActiveSpreadsheet().getActiveSheet();
  wsOptions = SpreadsheetApp.getActiveSpreadsheet().getSheetByName(optionsWsName[wsName]);
  options = wsOptions.getRange(1, 1, wsOptions.getLastRow(),3).getValues();
  Logger.log(ws.getName(), wsOptions.getName());
  if (mainWsName.indexOf(wsName)>-1 && c === firstLevelColumn && r > 1) {
    applyFirstLevelValidation(val,r );
  } else if (mainWsName.indexOf(wsName)>-1 && c === secondLevelColumn && r > 1) {
        applySecondLevelValidation(val,r );
  }
} //end onEdit

function applyFirstLevelValidation(val,r ) {
if (val === "") {
      ws.getRange(r, secondLevelColumn).clearContent();
      ws.getRange(r, secondLevelColumn).clearDataValidations();
      ws.getRange(r, thirdLevelColumn).clearContent();
      ws.getRange(r, thirdLevelColumn).clearDataValidations();
    } else {
    ws.getRange(r, secondLevelColumn).clearContent();
    ws.getRange(r, secondLevelColumn).clearDataValidations();
    ws.getRange(r, thirdLevelColumn).clearContent();
    ws.getRange(r, thirdLevelColumn).clearDataValidations();
    var filteredOptions = options.filter(function(o) { return o[0] === val });
    var listToApply = filteredOptions.map(function(o) { return o[1] });
    var cell = ws.getRange(r, secondLevelColumn);
    applyValidationToCell(listToApply,  cell);
}
} //end FirstLevel

function applySecondLevelValidation(val,r ) {
if (val === "") {
      ws.getRange(r, thirdLevelColumn).clearContent();
      ws.getRange(r, thirdLevelColumn).clearDataValidations();
    } else {
    ws.getRange(r, thirdLevelColumn).clearContent();
    var firstLevelColValue = ws.getRange(r, firstLevelColumn).getValue();
    var filteredOptions = options.filter(function(o) { return o[0] === firstLevelColValue && o[1] === val });
    var listToApply = filteredOptions.map(function(o) { return o[2] });
    var cell = ws.getRange(r, thirdLevelColumn);
    applyValidationToCell(listToApply,  cell);
}
} //end SecondLevel

function applyValidationToCell(list,  cell) {
  var rule = SpreadsheetApp.newDataValidation().requireValueInList(list).setAllowInvalid(false).build();
  cell.setDataValidation(rule);
 }