Data validation depending on condition Google Spreadsheets - validation

Question

In Google Spreadsheets, is it possible to make a cell data validation for a range of numbers depending on the result of a condition?
Example:
column1 column2
a if column1=a then show dropdown of (1,0) if b then (2,3) so [1,0]
a if column1=a then show dropdown of (1,0) if b then (2,3) so [1,0]
b if column1=a then show dropdown of (1,0) if b then (2,3) so [2,0]
a if column1=a then show dropdown of (1,0) if b then (2,3) so [1,0]

Answer 1

I am not exactly clear on what you want, but you can
have different dropdowns based on different values in
a cell. This code assumes the value to evaluate is in
cell A1 ('a', 'b', or another value). If A1=a then the
dropdown list comes from C1:C2. If A1=b then the dropdown
list is from D1:D2. Any other value in A1 removes the
valadation in B1. (Entering a or b in A1 will put the
valadation back).
function onEdit(e)
{
var sheet = SpreadsheetApp.getActiveSpreadsheet();
var sheetName= sheet.getSheetName();
if(sheetName=="Sheet1"){ //Only Sheet1
var editRange = sheet.getActiveRange();
var editRow = editRange.getRow();
var editCol = editRange.getColumn();
var lr = sheet.getLastRow()
var range = sheet.getRange("A1"); // Only apply on edit to cell Sheet1!A1
var rangeRowStart = range.getRow();
var rangeRowEnd = rangeRowStart + range.getHeight()-1;
var rangeColStart = range.getColumn();
var rangeColEnd = rangeColStart + range.getWidth()-1;
if (editRow >= rangeRowStart && editRow <= rangeRowEnd
&& editCol >= rangeColStart && editCol <= rangeColEnd)
{
drop()
}}}
function drop(){
var cell = SpreadsheetApp.getActive().getRange('B1');//set validation in B1
var ocell=SpreadsheetApp.getActive().getRange('B1').offset(0, -1).getValue()//evaluate value in A1
var cellVal=cell.getValue()
if(ocell=="a"){ //If A1=a dropdown list is C1:C2
var range = SpreadsheetApp.getActive().getRange('C1:C2');
var rule = SpreadsheetApp.newDataValidation().requireValueInRange(range).build();
cell.setDataValidation(rule)}
else if(ocell=="b"){ //if A1=b dropdown list = D1:D2
var range = SpreadsheetApp.getActive().getRange('D1:D2');
var rule = SpreadsheetApp.newDataValidation().requireValueInRange(range).build();
cell.setDataValidation(rule);}
else{ // If A1 is not a or b remove validation from B1
cell.clearDataValidations()}
}
If this is not what you are looking for explain and I can adjust.