I want to calculate and output the area of a year, but I keep showing the date - date

Question

enter code here
function processS2Collection(year,month, region) {
var startDate = ee.Date.fromYMD(year, month, 1);
var endDate = ee.Date.fromYMD(year, month+1, 1);
var collection = ee.ImageCollection("COPERNICUS/S2")
.filterDate('startDate, endDate')
.filterBounds(roi)
.filter(ee.Filter.lt('CLOUDY_PIXEL_PERCENTAGE', 80))
//.map(scaleS2Image)
.map(maskS2clouds)
.map(removeShadow)
.map(addSnowIce)
.map(addS2VIs)
.median() ;
var MNDWI_S2=collection.select('mNDWI');
var histogram = MNDWI_S2.reduceRegion({
reducer: ee.Reducer.histogram(),
geometry: roi,
scale: 30,
maxPixels: 1e13,
tileScale: 8
});
var threshold_S2 = otsu(histogram.get("mNDWI"));
var threshold = ee.Number(threshold_S2);
var mask = MNDWI_S2.gte(threshold);
print(threshold,'threshold')
var water_S2 = mask.updateMask(mask).rename("water");
var waterarea_S2_based=ee.Number((((water_S2.multiply(0.000001).multiply(ee.Image.pixelArea()))
.reduceRegion({
reducer: ee.Reducer.sum(),
geometry: roi,
scale: 30,
maxPixels: 1e13,})).get('water')))
Map.addLayer(water_S2.clip(table),{min:0,max:1,palette:['#DDDDDD','#FF3300']},'water_S2_otsu_based');
print('waterarea_S2_based',waterarea_S2_based)
}
for (var i=1; i<=11; i++) {
var month=i;
processS2Collection(2017,month, roi);
}
//I want to calculate and output the area of a year, but I keep showing the date
//Source code link:https://code.earthengine.google.com/51a90e5845e6732d0f241fa4fda64c8a
Anyone has a solution?