Area Estimation for Several Regions and Several Dates in GEE

Question

Following the previous question, I have a new question. From the following code, I estimate the water areas for selected regions in Google Earth Engine. However, as you could see from the second line of the code, it only estimates for selected date (.filterDate("2010-03-01");). I want it to estimate for all the available dates (months in the dataset) and the regions. Shortly, I would like to add a simple loop for the dates in this code.

//Opening the JRC Water Data
var water_data = ee.ImageCollection("JRC/GSW1_2/MonthlyHistory").filterDate("2010-03-01");
var water_area = ee.Image(water_data.first())

//Creating Region Variable
var turkeyProvinces = ee.FeatureCollection("FAO/GAUL_SIMPLIFIED_500m/2015/level1")
    .filter(ee.Filter.eq("ADM0_NAME", "Turkey"));

//Calculating Water Areas
var calculateClassArea = function(feature) {
    var areas = water_area.eq(2).selfMask().multiply(ee.Image.pixelArea()).divide(1e6)
    .reduceRegion({
      reducer: ee.Reducer.sum(),
      geometry: feature.geometry(),
      scale: 30,
      maxPixels: 1e10
    })

    return feature.set(areas)
}
var waterAreas = turkeyProvinces.map(calculateClassArea);

//Exporting the Results
Export.table.toDrive({
    collection: waterAreas,
    description: 'water_area_by_province',
    folder: 'earthengine',
    fileNamePrefix: 'water_area_by_province',
    fileFormat: 'CSV',
    selectors: ['ADM1_NAME', 'water']
    })

Here is the Google Earth Engine link: https://code.earthengine.google.com/f024358da930db6444ea29820867a7dd

Answer 1

I want to paste the solution to the problem from the discussion with Kuik in the previous post's comment section:

//Opening the JRC Water Data
var water_data = ee.ImageCollection("JRC/GSW1_2/MonthlyHistory");

//Creating Region Variable
var turkeyProvinces = ee.FeatureCollection("FAO/GAUL_SIMPLIFIED_500m/2015/level1")
    .filter(ee.Filter.eq("ADM0_NAME", "Turkey"));

//Calculating Water Areas
var waterAreas = water_data.map(function(image){
  var water = image.eq(2).selfMask().multiply(ee.Image.pixelArea()).divide(1e6);
  var areas = water.reduceRegions({
      reducer: ee.Reducer.sum(),
      collection: turkeyProvinces,
      scale: 30
    });
  return areas.map(function(feat){
  return feat.set(image.toDictionary(['system:time_start']));
  });
}).flatten().select(['ADM1_NAME', 'sum','system:time_start']);

//Exporting the Results
Export.table.toDrive({
    collection: waterAreas,
    description: 'water_area_by_province',
    folder: 'earthengine',
    fileNamePrefix: 'water_area_by_province',
    fileFormat: 'CSV',
    selectors: ['ADM1_NAME', 'sum','system:time_start']
    })