Use leaflet-hash

Vendorfile

@@ -23,6 +23,10 @@ folder 'vendor/assets' do
     from 'git://github.com/jfirebaugh/leaflet-osm.git' do
       file 'leaflet.osm.js', 'leaflet-osm.js'
     end
+
+    from 'git://github.com/mlevans/leaflet-hash.git' do
+      file 'leaflet.hash.js', 'leaflet-hash.js'
+    end
   end
 
   folder 'ohauth' do

app/assets/javascripts/application.js

@@ -5,6 +5,7 @@
 //= require augment
 //= require leaflet
 //= require leaflet.osm
+//= require leaflet.hash
 //= require leaflet.zoom
 //= require leaflet.extend
 //= require leaflet.locationfilter

app/assets/javascripts/index.js

@@ -19,6 +19,8 @@ $(document).ready(function () {
 
   map.attributionControl.setPrefix('');
 
+  new L.Hash(map);
+
   var layers = [
     new L.OSM.Mapnik({
       attribution: '',

vendor/assets/leaflet/leaflet.hash.js

@@ -0,0 +1,162 @@
+(function(window) {
+	var HAS_HASHCHANGE = (function() {
+		var doc_mode = window.documentMode;
+		return ('onhashchange' in window) &&
+			(doc_mode === undefined || doc_mode > 7);
+	})();
+
+	L.Hash = function(map) {
+		this.onHashChange = L.Util.bind(this.onHashChange, this);
+
+		if (map) {
+			this.init(map);
+		}
+	};
+
+	L.Hash.parseHash = function(hash) {
+		if(hash.indexOf('#') === 0) {
+			hash = hash.substr(1);
+		}
+		var args = hash.split("/");
+		if (args.length == 3) {
+			var zoom = parseInt(args[0], 10),
+			lat = parseFloat(args[1]),
+			lon = parseFloat(args[2]);
+			if (isNaN(zoom) || isNaN(lat) || isNaN(lon)) {
+				return false;
+			} else {
+				return {
+					center: new L.LatLng(lat, lon),
+					zoom: zoom
+				};
+			}
+		} else {
+			return false;
+		}
+	};
+
+	L.Hash.formatHash = function(map) {
+		var center = map.getCenter(),
+		    zoom = map.getZoom(),
+		    precision = Math.max(0, Math.ceil(Math.log(zoom) / Math.LN2));
+
+		return "#" + [zoom,
+			center.lat.toFixed(precision),
+			center.lng.toFixed(precision)
+		].join("/");
+	},
+
+	L.Hash.prototype = {
+		map: null,
+		lastHash: null,
+
+		parseHash: L.Hash.parseHash,
+		formatHash: L.Hash.formatHash,
+
+		init: function(map) {
+			this.map = map;
+
+			// reset the hash
+			this.lastHash = null;
+			this.onHashChange();
+
+			if (!this.isListening) {
+				this.startListening();
+			}
+		},
+
+		remove: function() {
+			if (this.changeTimeout) {
+				clearTimeout(this.changeTimeout);
+			}
+
+			if (this.isListening) {
+				this.stopListening();
+			}
+
+			this.map = null;
+		},
+
+		onMapMove: function() {
+			// bail if we're moving the map (updating from a hash),
+			// or if the map is not yet loaded
+
+			if (this.movingMap || !this.map._loaded) {
+				return false;
+			}
+
+			var hash = this.formatHash(this.map);
+			if (this.lastHash != hash) {
+				location.replace(hash);
+				this.lastHash = hash;
+			}
+		},
+
+		movingMap: false,
+		update: function() {
+			var hash = location.hash;
+			if (hash === this.lastHash) {
+				return;
+			}
+			var parsed = this.parseHash(hash);
+			if (parsed) {
+				this.movingMap = true;
+
+				this.map.setView(parsed.center, parsed.zoom);
+
+				this.movingMap = false;
+			} else {
+				this.onMapMove(this.map);
+			}
+		},
+
+		// defer hash change updates every 100ms
+		changeDefer: 100,
+		changeTimeout: null,
+		onHashChange: function() {
+			// throttle calls to update() so that they only happen every
+			// `changeDefer` ms
+			if (!this.changeTimeout) {
+				var that = this;
+				this.changeTimeout = setTimeout(function() {
+					that.update();
+					that.changeTimeout = null;
+				}, this.changeDefer);
+			}
+		},
+
+		isListening: false,
+		hashChangeInterval: null,
+		startListening: function() {
+			this.map.on("moveend", this.onMapMove, this);
+
+			if (HAS_HASHCHANGE) {
+				L.DomEvent.addListener(window, "hashchange", this.onHashChange);
+			} else {
+				clearInterval(this.hashChangeInterval);
+				this.hashChangeInterval = setInterval(this.onHashChange, 50);
+			}
+			this.isListening = true;
+		},
+
+		stopListening: function() {
+			this.map.off("moveend", this.onMapMove, this);
+
+			if (HAS_HASHCHANGE) {
+				L.DomEvent.removeListener(window, "hashchange", this.onHashChange);
+			} else {
+				clearInterval(this.hashChangeInterval);
+			}
+			this.isListening = false;
+		}
+	};
+	L.hash = function(map) {
+		return new L.Hash(map);
+	};
+	L.Map.prototype.addHash = function() {
+		this._hash = L.hash(this);
+	};
+	L.Map.prototype.removeHash = function() {
+		this._hash.remove();
+	};
+})(window);