Use a extra loader class to simplify code

index.js

@@ -1,7 +1,7 @@
 var OverpassLayer = require('overpass-layer')
 var OverpassLayerList = require('overpass-layer').List
 var OverpassFrontend = require('overpass-frontend')
-var OpenStreetBrowserCategory = require('./src/OpenStreetBrowserCategory')
+var OpenStreetBrowserLoader = require('./src/OpenStreetBrowserLoader')
 
 var map
 
@@ -20,6 +20,8 @@ window.onload = function() {
   )
   osm_mapnik.addTo(map)
 
-  var category = new OpenStreetBrowserCategory("gastro")
-  category.addTo(map, document.getElementById('info'))
+
+  OpenStreetBrowserLoader('gastro', function (err, category) {
+    category.addTo(map, document.getElementById('info'))
+  })
 }

src/OpenStreetBrowserCategory.js

@@ -1,34 +1,16 @@
 var OverpassLayer = require('overpass-layer')
 var OverpassLayerList = require('overpass-layer').List
 
-function OpenStreetBrowserCategory (id) {
-  function reqListener (req) {
-    var data = JSON.parse(req.responseText)
-
-    this.layer = new OverpassLayer(data.query, data)
-
-    if (this.autoAdd) {
-      this.addTo(this.map, this.parentDom)
-      this.autoAdd = false
-    }
-  }
-
-  var req = new XMLHttpRequest()
-  req.addEventListener("load", reqListener.bind(this, req))
-  req.open("GET", "categories/" + id + ".json")
-  req.send()
+function OpenStreetBrowserCategory (data) {
+  this.layer = new OverpassLayer(data.query, data)
 }
 
 OpenStreetBrowserCategory.prototype.addTo = function (map, parentDom) {
   this.map = map
   this.parentDom = parentDom
 
-  if (this.layer) {
-    this.layer.addTo(this.map)
-    new OverpassLayerList(this.parentDom, this.layer);
-  } else {
-    this.autoAdd = true
-  }
+  this.layer.addTo(this.map)
+  new OverpassLayerList(this.parentDom, this.layer);
 }
 
 module.exports = OpenStreetBrowserCategory

src/OpenStreetBrowserLoader.js

@@ -0,0 +1,19 @@
+var OpenStreetBrowserIndex = require('./OpenStreetBrowserIndex')
+var OpenStreetBrowserCategory = require('./OpenStreetBrowserCategory')
+
+function OpenStreetBrowserLoader (id, callback) {
+  function reqListener (req) {
+    var data = JSON.parse(req.responseText)
+
+    var layer = new OpenStreetBrowserCategory(data)
+
+    callback(null, layer)
+  }
+
+  var req = new XMLHttpRequest()
+  req.addEventListener("load", reqListener.bind(this, req))
+  req.open("GET", "categories/" + id + ".json")
+  req.send()
+}
+
+module.exports = OpenStreetBrowserLoader