diff --git a/src/Mapscii.coffee b/src/Mapscii.coffee
deleted file mode 100644
index c463dc5..0000000
--- a/src/Mapscii.coffee
+++ /dev/null
@@ -1,226 +0,0 @@
-###
-  mapscii - Terminal Map Viewer
-  by Michael Strassburger <codepoet@cpan.org>
-
-  UI and central command center
-###
-
-keypress = require 'keypress'
-TermMouse = require 'term-mouse'
-Promise = require 'bluebird'
-
-Renderer = require './Renderer'
-TileSource = require './TileSource'
-utils = require './utils'
-config = require './config'
-
-module.exports = class Mapscii
-  width: null
-  height: null
-  canvas: null
-  mouse: null
-
-  mouseDragging: false
-  mousePosition:
-    x: 0, y: 0
-
-  tileSource: null
-  renderer: null
-
-  zoom: 0
-  center:
-    # sf lat: 37.787946, lon: -122.407522
-    # iceland lat: 64.124229, lon: -21.811552
-    # rgbg
-    # lat: 49.019493, lon: 12.098341
-    lat: 52.51298, lon: 13.42012
-
-  minZoom: null
-
-  constructor: (options) ->
-    config[key] = val for key, val of options
-
-  init: ->
-    Promise
-    .resolve()
-    .then =>
-      unless config.headless
-        @_initKeyboard()
-        @_initMouse()
-
-      @_initTileSource()
-
-    .then =>
-      @_initRenderer()
-
-    .then =>
-      @_draw()
-      .then => @notify("Welcome to MapSCII! Use your cursors to navigate, a/z to zoom, q to quit.")
-
-  _initTileSource: ->
-    @tileSource = new TileSource()
-    @tileSource.init config.source
-
-  _initKeyboard: ->
-    keypress config.input
-    config.input.setRawMode true if config.input.setRawMode
-    config.input.resume()
-
-    config.input.on 'keypress', (ch, key) => @_onKey key
-
-  _initMouse: ->
-    @mouse = TermMouse input: config.input, output: config.output
-    @mouse.start()
-
-    @mouse.on 'click', (event) => @_onClick event
-    @mouse.on 'scroll', (event) => @_onMouseScroll event
-    @mouse.on 'move', (event) => @_onMouseMove event
-
-  _initRenderer: ->
-    @renderer = new Renderer config.output, @tileSource
-    @renderer.loadStyleFile config.styleFile
-
-    config.output.on 'resize', =>
-      @_resizeRenderer()
-      @_draw()
-
-    @_resizeRenderer()
-    @zoom = if config.initialZoom isnt null then config.initialZoom else @minZoom
-
-  _resizeRenderer: (cb) ->
-    if config.size
-      @width = config.size.width
-      @height = config.size.height
-    else
-      @width = config.output.columns >> 1 << 2
-      @height = config.output.rows * 4 - 4
-
-    @minZoom = 4-Math.log(4096/@width)/Math.LN2
-
-    @renderer.setSize @width, @height
-
-  _updateMousePosition: (event) ->
-    projected =
-      x: (event.x-.5)*2
-      y: (event.y-.5)*4
-
-    size = utils.tilesizeAtZoom @zoom
-    [dx, dy] = [projected.x-@width/2, projected.y-@height/2]
-
-    z = utils.baseZoom @zoom
-    center = utils.ll2tile @center.lon, @center.lat, z
-
-    @mousePosition = utils.normalize utils.tile2ll center.x+(dx/size), center.y+(dy/size), z
-
-  _onClick: (event) ->
-    return if event.x < 0 or event.x > @width/2 or event.y < 0 or event.y > @height/4
-    @_updateMousePosition event
-
-    if @mouseDragging and event.button is "left"
-      @mouseDragging = false
-    else
-      @setCenter @mousePosition.lat, @mousePosition.lon
-
-    @_draw()
-
-  _onMouseScroll: (event) ->
-    @_updateMousePosition event
-    # TODO: handle .x/y for directed zoom
-    @zoomBy config.zoomStep * if event.button is "up" then 1 else -1
-    @_draw()
-
-  _onMouseMove: (event) ->
-    return if event.x < 0 or event.x > @width/2 or event.y < 0 or event.y > @height/4
-    return if config.mouseCallback and not config.mouseCallback event
-
-    # start dragging
-    if event.button is "left"
-      if @mouseDragging
-        dx = (@mouseDragging.x-event.x)*2
-        dy = (@mouseDragging.y-event.y)*4
-
-        size = utils.tilesizeAtZoom @zoom
-
-        newCenter = utils.tile2ll @mouseDragging.center.x+(dx/size),
-          @mouseDragging.center.y+(dy/size),
-          utils.baseZoom(@zoom)
-
-        @setCenter newCenter.lat, newCenter.lon
-
-        @_draw()
-
-      else
-        @mouseDragging =
-          x: event.x,
-          y: event.y,
-          center: utils.ll2tile @center.lon, @center.lat, utils.baseZoom(@zoom)
-
-    @_updateMousePosition event
-    @notify @_getFooter()
-
-  _onKey: (key) ->
-    if config.keyCallback and not config.keyCallback key
-      return
-
-    # check if the pressed key is configured
-    draw = switch key?.name
-      when "q"
-        if config.quitCallback
-          config.quitCallback()
-        else
-          process.exit 0
-
-      when "a" then @zoomBy config.zoomStep
-      when "z", "y"
-        @zoomBy -config.zoomStep
-
-      when "left" then @moveBy 0, -8/Math.pow(2, @zoom)
-      when "right" then @moveBy 0, 8/Math.pow(2, @zoom)
-      when "up" then @moveBy 6/Math.pow(2, @zoom), 0
-      when "down" then @moveBy -6/Math.pow(2, @zoom), 0
-
-      when "c"
-        config.useBraille = !config.useBraille
-        true
-
-      else
-        null
-
-    if draw isnt null
-      @_draw()
-
-  _draw: ->
-    @renderer
-    .draw @center, @zoom
-    .then (frame) =>
-      @_write frame
-      @notify @_getFooter()
-    .catch =>
-      @notify "renderer is busy"
-
-  _getFooter: ->
-    # tile = utils.ll2tile @center.lon, @center.lat, @zoom
-    # "tile: #{utils.digits tile.x, 3}, #{utils.digits tile.x, 3}   "+
-
-    "center: #{utils.digits @center.lat, 3}, #{utils.digits @center.lon, 3}   "+
-    "zoom: #{utils.digits @zoom, 2}   "+
-    "mouse: #{utils.digits @mousePosition.lat, 3}, #{utils.digits @mousePosition.lon, 3} "
-
-  notify: (text) ->
-    config.onUpdate() if config.onUpdate
-    @_write "\r\x1B[K"+text unless config.headless
-
-  _write: (output) ->
-    config.output.write output
-
-  zoomBy: (step) ->
-    return @zoom = @minZoom if @zoom+step < @minZoom
-    return @zoom = config.maxZoom if @zoom+step > config.maxZoom
-
-    @zoom += step
-
-  moveBy: (lat, lon) ->
-    @setCenter @center.lat+lat, @center.lon+lon
-
-  setCenter: (lat, lon) ->
-    @center = utils.normalize lon: lon, lat: lat
diff --git a/src/Mapscii.js b/src/Mapscii.js
new file mode 100644
index 0000000..6d230c8
--- /dev/null
+++ b/src/Mapscii.js
@@ -0,0 +1,287 @@
+/*
+  mapscii - Terminal Map Viewer
+  by Michael Strassburger <codepoet@cpan.org>
+
+  UI and central command center
+*/
+'use strict';
+const keypress = require('keypress');
+const TermMouse = require('term-mouse');
+
+const Renderer = require('./Renderer');
+const TileSource = require('./TileSource');
+const utils = require('./utils');
+let config = require('./config');
+
+class Mapscii {
+  constructor(options) {
+    this.width = null;
+    this.height = null;
+    this.canvas = null;
+    this.mouse = null;
+
+    this.mouseDragging = false;
+    this.mousePosition = {
+      x: 0,
+      y: 0,
+    };
+
+    this.tileSource = null;
+    this.renderer = null;
+
+    this.zoom = 0;
+    // sf lat: 37.787946, lon: -122.407522
+    // iceland lat: 64.124229, lon: -21.811552
+    // rgbg
+    // lat: 49.019493, lon: 12.098341
+    this.center = {
+      lat: 52.51298,
+      lon: 13.42012,
+    };
+
+    this.minZoom = null;
+    config = Object.assign(config, options);
+  }
+
+  init() {
+    return new Promise((resolve) => {
+      if (!config.headless) {
+        this._initKeyboard();
+        this._initMouse();
+      }
+      this._initTileSource();
+      this._initRenderer();
+      this._draw();
+      this.notify("Welcome to MapSCII! Use your cursors to navigate, a/z to zoom, q to quit.");
+      resolve();
+    });
+  }
+
+
+  _initTileSource() {
+    this.tileSource = new TileSource();
+    this.tileSource.init(config.source);
+  }
+
+  _initKeyboard() {
+    keypress(config.input);
+    if (config.input.setRawMode) {
+      config.input.setRawMode(true);
+    }
+    config.input.resume();
+
+    config.input.on('keypress', (ch, key) => this._onKey(key));
+  }
+
+  _initMouse() {
+    this.mouse = TermMouse({
+      input: config.input,
+      output: config.output,
+    });
+    this.mouse.start();
+
+    this.mouse.on('click', (event) => this._onClick(event));
+    this.mouse.on('scroll', (event) => this._onMouseScroll(event));
+    this.mouse.on('move', (event) => this._onMouseMove(event));
+  }
+
+  _initRenderer() {
+    this.renderer = new Renderer(config.output, this.tileSource);
+    this.renderer.loadStyleFile(config.styleFile);
+
+    config.output.on('resize', () => {
+      this._resizeRenderer();
+      this._draw();
+    });
+
+    this._resizeRenderer()
+    this.zoom = (config.initialZoom !== null) ? config.initialZoom : this.minZoom;
+  }
+
+  _resizeRenderer(cb) {
+    if (config.size) {
+      this.width = config.size.width;
+      this.height = config.size.height;
+    } else {
+      this.width = config.output.columns >> 1 << 2;
+      this.height = config.output.rows * 4 - 4;
+    }
+
+    this.minZoom = 4-Math.log(4096/this.width)/Math.LN2;
+
+    this.renderer.setSize(this.width, this.height);
+  }
+
+  _updateMousePosition(event) {
+    const projected = {
+      x: (event.x-0.5)*2,
+      y: (event.y-0.5)*4,
+    };
+
+    const size = utils.tilesizeAtZoom(this.zoom);
+    const [dx, dy] = [projected.x-this.width/2, projected.y-this.height/2];
+
+    const z = utils.baseZoom(this.zoom);
+    const center = utils.ll2tile(this.center.lon, this.center.lat, z);
+
+    this.mousePosition = utils.normalize(utils.tile2ll(center.x+(dx/size), center.y+(dy/size), z));
+  }
+
+  _onClick(event) {
+    if (event.x < 0 || event.x > this.width/2 || event.y < 0 || event.y > this.height/4) {
+      return;
+    }
+    this._updateMousePosition(event);
+
+    if (this.mouseDragging && event.button === 'left') {
+      this.mouseDragging = false;
+    } else {
+      this.setCenter(this.mousePosition.lat, this.mousePosition.lon);
+    }
+
+    this._draw();
+  }
+
+  _onMouseScroll(event) {
+    this._updateMousePosition(event);
+    // TODO: handle .x/y for directed zoom
+    this.zoomBy(config.zoomStep * (event.button === 'up' ? 1 : -1));
+    this._draw();
+  }
+
+  _onMouseMove(event) {
+    if (event.x < 0 || event.x > this.width/2 || event.y < 0 || event.y > this.height/4) {
+      return;
+    }
+    if (config.mouseCallback && !config.mouseCallback(event)) {
+      return;
+    }
+
+    // start dragging
+    if (event.button === 'left') {
+      if (this.mouseDragging) {
+        const dx = (this.mouseDragging.x-event.x)*2;
+        const dy = (this.mouseDragging.y-event.y)*4;
+
+        const size = utils.tilesizeAtZoom(this.zoom);
+
+        const newCenter = utils.tile2ll(
+          this.mouseDragging.center.x+(dx/size),
+          this.mouseDragging.center.y+(dy/size),
+          utils.baseZoom(this.zoom),
+        );
+
+        this.setCenter(newCenter.lat, newCenter.lon);
+
+        this._draw();
+
+      } else {
+        this.mouseDragging = {
+          x: event.x,
+          y: event.y,
+          center: utils.ll2tile(this.center.lon, this.center.lat, utils.baseZoom(this.zoom)),
+        }
+      }
+    }
+
+    this._updateMousePosition(event);
+    this.notify(this._getFooter());
+  }
+
+  _onKey(key) {
+    if (config.keyCallback && !config.keyCallback(key)) return;
+    if (!key || !key.name) return;
+
+    // check if the pressed key is configured
+    let draw = true;
+    switch (key.name) {
+      case 'q':
+        if (config.quitCallback) {
+          config.quitCallback();
+        } else {
+          process.exit(0);
+        }
+        break;
+      case 'a':
+        this.zoomBy(config.zoomStep);
+        break;
+      case 'z', 'y':
+        this.zoomBy(-config.zoomStep);
+        break;
+      case 'left':
+        this.moveBy(0, -8/Math.pow(2, this.zoom));
+        break;
+      case 'right':
+        this.moveBy(0, 8/Math.pow(2, this.zoom));
+        break;
+      case 'up':
+        this.moveBy(6/Math.pow(2, this.zoom), 0);
+        break;
+      case 'down':
+        this.moveBy(-6/Math.pow(2, this.zoom), 0);
+        break;
+      case 'c':
+        config.useBraille = !config.useBraille;
+        break;
+      default:
+        draw = false;
+    }
+
+    if (draw !== null) {
+      this._draw();
+    }
+  }
+
+  _draw() {
+    this.renderer.draw(this.center, this.zoom).then((frame) => {
+      this._write(frame);
+      this.notify(this._getFooter());
+    }).catch(() => {
+      this.notify('renderer is busy');
+    });
+  }
+
+  _getFooter() {
+    // tile = utils.ll2tile(this.center.lon, this.center.lat, this.zoom);
+    // `tile: ${utils.digits(tile.x, 3)}, ${utils.digits(tile.x, 3)}   `+
+
+    return `center: ${utils.digits(this.center.lat, 3)}, ${utils.digits(this.center.lon, 3)}   `+
+      `zoom: ${utils.digits(this.zoom, 2)}   `+
+      `mouse: ${utils.digits(this.mousePosition.lat, 3)}, ${utils.digits(this.mousePosition.lon, 3)} `;
+  }
+
+  notify(text) {
+    config.onUpdate && config.onUpdate();
+    if (!config.headless) {
+      this._write('\r\x1B[K' + text);
+    }
+  }
+
+  _write(output) {
+    config.output.write(output);
+  }
+
+  zoomBy(step) {
+    if (this.zoom+step < this.minZoom) {
+      return this.zoom = this.minZoom;
+    }
+    if (this.zoom+step > config.maxZoom) {
+      return this.zoom = config.maxZoom;
+    }
+
+    this.zoom += step;
+  }
+
+  moveBy(lat, lon) {
+    this.setCenter(this.center.lat+lat, this.center.lon+lon);
+  }
+
+  setCenter(lat, lon) {
+    this.center = utils.normalize({
+      lon: lon,
+      lat: lat,
+    });
+  }
+}
+
+module.exports = Mapscii;