Use localized placeholder for expected date filter format

data/core.yaml

@@ -2312,6 +2312,8 @@ en:
     west: "W"
     coordinate: "{coordinate}{direction}"
     coordinate_pair: "{latitude}, {longitude}"
+    # translate the letters but leave the format the same
+    year_month_day: "YYYY-MM-DD"
   wikidata:
     identifier: "Identifier"
     label: "Label"

dist/locales/en.json

@@ -2858,7 +2858,8 @@
             "east": "E",
             "west": "W",
             "coordinate": "{coordinate}{direction}",
-            "coordinate_pair": "{latitude}, {longitude}"
+            "coordinate_pair": "{latitude}, {longitude}",
+            "year_month_day": "YYYY-MM-DD"
         },
         "wikidata": {
             "identifier": "Identifier",

modules/ui/sections/photo_overlays.js

@@ -5,6 +5,7 @@ import {
 import { t } from '../../core/localizer';
 import { uiTooltip } from '../tooltip';
 import { uiSection } from '../section';
+import { utilGetSetValue } from '../../util';
 
 export function uiSectionPhotoOverlays(context) {
 
@@ -214,9 +215,9 @@ export function uiSectionPhotoOverlays(context) {
             .append('input')
             .attr('type', 'date')
             .attr('class', 'list-item-input')
-            .attr('placeholder', 'dd/mm/yyyy')
-            .property('value', function(d) {
-                return context.photos().dateFilterValue(d);
+            .attr('placeholder', t('units.year_month_day'))
+            .each(function(d) {
+                utilGetSetValue(d3_select(this), context.photos().dateFilterValue(d) || '');
             })
             .on('change', function(d3_event, d) {
                 var value = d3_select(this).property('value');