From f97aee7fa2ee2e3acebe0f984f57b98aecf3ff45 Mon Sep 17 00:00:00 2001
From: Anton Khorev <tony29@yandex.ru>
Date: Wed, 29 Jan 2025 13:35:01 +0300
Subject: [PATCH 1/3] Don't remove-readd standard layer when layerParam is not
 empty in map.updateLayers

---
 app/assets/javascripts/leaflet.map.js | 21 ++++++++++-----------
 1 file changed, 10 insertions(+), 11 deletions(-)

diff --git a/app/assets/javascripts/leaflet.map.js b/app/assets/javascripts/leaflet.map.js
index 1e9174efa6e..2bf097cea0c 100644
--- a/app/assets/javascripts/leaflet.map.js
+++ b/app/assets/javascripts/leaflet.map.js
@@ -116,20 +116,19 @@ L.OSM.Map = L.Map.extend({
   },
 
   updateLayers: function (layerParam) {
-    var layers = layerParam || "O",
-      layersAdded = "";
-
-    for (let i = this.baseLayers.length - 1; i >= 0; i--) {
-      if (layers.indexOf(this.baseLayers[i].options.code) >= 0) {
-        this.addLayer(this.baseLayers[i]);
-        layersAdded = layersAdded + this.baseLayers[i].options.code;
-      } else if (i === 0 && layersAdded === "") {
-        this.addLayer(this.baseLayers[i]);
-      } else {
-        this.removeLayer(this.baseLayers[i]);
+    const oldBaseLayer = this.getMapBaseLayer();
+    let newBaseLayer;
+
+    for (const layer of this.baseLayers) {
+      if (!newBaseLayer || layerParam.includes(layer.options.code)) {
+        newBaseLayer = layer;
       }
     }
 
+    if (newBaseLayer !== oldBaseLayer) {
+      if (oldBaseLayer) this.removeLayer(oldBaseLayer);
+      if (newBaseLayer) this.addLayer(newBaseLayer);
+    }
   },
 
   getLayersCode: function () {

From b21c9d132600ae71ecc8edb4cd1b6e873302435e Mon Sep 17 00:00:00 2001
From: Anton Khorev <tony29@yandex.ru>
Date: Tue, 10 Dec 2024 00:31:59 +0300
Subject: [PATCH 2/3] Add map.getMapBaseLayer()

---
 app/assets/javascripts/leaflet.map.js | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/app/assets/javascripts/leaflet.map.js b/app/assets/javascripts/leaflet.map.js
index 2bf097cea0c..e2bfd64a5a3 100644
--- a/app/assets/javascripts/leaflet.map.js
+++ b/app/assets/javascripts/leaflet.map.js
@@ -142,11 +142,8 @@ L.OSM.Map = L.Map.extend({
   },
 
   getMapBaseLayerId: function () {
-    var baseLayerId;
-    this.eachLayer(function (layer) {
-      if (layer.options && layer.options.keyid) baseLayerId = layer.options.keyid;
-    });
-    return baseLayerId;
+    const layer = this.getMapBaseLayer();
+    if (layer) return layer.options.layerId;
   },
 
   getMapBaseLayer: function () {

From 8faa35915ef4570a0c857a63700bbdb7aaca9295 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Minh=20Nguy=E1=BB=85n?= <mxn@1ec5.org>
Date: Sat, 18 Jul 2026 12:11:54 -0700
Subject: [PATCH 3/3] Fixed slippy map tests

These tests assume the default layer is Standard (M), not a vector style like Historical.
---
 test/javascripts/osm_test.js | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/test/javascripts/osm_test.js b/test/javascripts/osm_test.js
index c5be6b5f6a5..b6f1adedc0f 100644
--- a/test/javascripts/osm_test.js
+++ b/test/javascripts/osm_test.js
@@ -339,7 +339,7 @@ describe("OSM", function () {
     it("creates a location cookie value", function () {
       $("body").append("<div id='map'>");
       const map = new L.OSM.Map("map", { center: [57.6247, -3.6845], zoom: 9 });
-      map.updateLayers("");
+      map.updateLayers("M");
       expect(OSM.locationCookie(map)).to.eq("-3.685|57.625|9|M");
       $("#map").remove();
     });
@@ -347,7 +347,7 @@ describe("OSM", function () {
     it("respects zoomPrecision", function () {
       $("body").append("<div id='map'>");
       const map = new L.OSM.Map("map", { center: [57.6247, -3.6845], zoom: 9 });
-      map.updateLayers("");
+      map.updateLayers("M");
       expect(OSM.locationCookie(map)).to.eq("-3.685|57.625|9|M");
       // map.setZoom() doesn't update the zoom level for some reason
       // using map._zoom here to update the zoom level manually