diff --git a/src/Eleventy.js b/src/Eleventy.js
index c9d6d2d33..aa6cde030 100644
--- a/src/Eleventy.js
+++ b/src/Eleventy.js
@@ -11,191 +11,197 @@ const config = require("./Config");
 const bench = require("./BenchmarkManager");
 const debug = require("debug")("Eleventy");
 
-function Eleventy(input, output) {
-  this.config = config.getConfig();
-  this.configPath = null;
-  this.isVerbose = true;
-  this.isDebug = false;
-  this.isDryRun = false;
+class Eleventy {
+  constructor(input, output) {
+    this.config = config.getConfig();
+    this.configPath = null;
+    this.isVerbose = true;
+    this.isDebug = false;
+    this.isDryRun = false;
 
-  this.start = new Date();
-  this.formatsOverride = null;
-  this.eleventyServe = new EleventyServe();
+    this.start = new Date();
+    this.formatsOverride = null;
+    this.eleventyServe = new EleventyServe();
 
-  this.rawInput = input;
-  this.rawOutput = output;
+    this.rawInput = input;
+    this.rawOutput = output;
 
-  this.watchTargets = new EleventyWatchTargets();
-  this.watchTargets.watchJavaScriptDependencies = this.config.watchJavaScriptDependencies;
+    this.watchTargets = new EleventyWatchTargets();
+    this.watchTargets.watchJavaScriptDependencies = this.config.watchJavaScriptDependencies;
+  }
 
-  this.initDirs();
-}
+  get input() {
+    return this.rawInput || this.config.dir.input;
+  }
 
-Eleventy.prototype.initDirs = function() {
-  this.input = this.rawInput || this.config.dir.input;
-  this.inputDir = TemplatePath.getDir(this.input);
-  this.outputDir = this.rawOutput || this.config.dir.output;
+  get inputDir() {
+    return TemplatePath.getDir(this.input);
+  }
 
-  this.eleventyServe.setOutputDir(this.outputDir);
-};
+  get outputDir() {
+    let dir = this.rawOutput || this.config.dir.output;
+    if (dir !== this._savedOutputDir) {
+      this.eleventyServe.setOutputDir(dir);
+    }
+    this._savedOutputDir = dir;
 
-Eleventy.prototype.setDryRun = function(isDryRun) {
-  this.isDryRun = !!isDryRun;
-};
+    return dir;
+  }
 
-Eleventy.prototype.setPassthroughAll = function(isPassthroughAll) {
-  this.isPassthroughAll = !!isPassthroughAll;
-};
+  setDryRun(isDryRun) {
+    this.isDryRun = !!isDryRun;
+  }
 
-Eleventy.prototype.setPathPrefix = function(pathPrefix) {
-  if (pathPrefix || pathPrefix === "") {
-    config.setPathPrefix(pathPrefix);
-    this.config = config.getConfig();
+  setPassthroughAll(isPassthroughAll) {
+    this.isPassthroughAll = !!isPassthroughAll;
   }
-};
 
-Eleventy.prototype.setWatchTargets = function(watchTargets) {
-  this.watchTargets = watchTargets;
-};
+  setPathPrefix(pathPrefix) {
+    if (pathPrefix || pathPrefix === "") {
+      config.setPathPrefix(pathPrefix);
+      this.config = config.getConfig();
+    }
+  }
 
-Eleventy.prototype.setConfigPathOverride = function(configPath) {
-  if (configPath) {
-    this.configPath = configPath;
+  setWatchTargets(watchTargets) {
+    this.watchTargets = watchTargets;
+  }
 
-    config.setProjectConfigPath(configPath);
-    this.config = config.getConfig();
+  setConfigPathOverride(configPath) {
+    if (configPath) {
+      this.configPath = configPath;
 
-    this.initDirs();
+      config.setProjectConfigPath(configPath);
+      this.config = config.getConfig();
+    }
   }
-};
-
-Eleventy.prototype.restart = async function() {
-  debug("Restarting");
-  this.start = new Date();
-  templateCache.clear();
-  bench.reset();
-  this.eleventyFiles.restart();
-
-  // reload package.json values (if applicable)
-  // TODO only reset this if it changed
-  delete require.cache[TemplatePath.localPath("package.json")];
-
-  this.initDirs();
-  await this.init();
-};
-
-Eleventy.prototype.finish = function() {
-  bench.finish();
-
-  (this.logger || console).log(this.logFinished());
-  debug("Finished writing templates.");
-};
-
-Eleventy.prototype.logFinished = function() {
-  if (!this.writer) {
-    throw new Error(
-      "Did you call Eleventy.init to create the TemplateWriter instance? Hint: you probably didn’t."
-    );
+
+  async restart() {
+    debug("Restarting");
+    this.start = new Date();
+    templateCache.clear();
+    bench.reset();
+    this.eleventyFiles.restart();
+
+    // reload package.json values (if applicable)
+    // TODO only reset this if it changed
+    delete require.cache[TemplatePath.localPath("package.json")];
+
+    await this.init();
   }
 
-  let ret = [];
+  finish() {
+    bench.finish();
 
-  let writeCount = this.writer.getWriteCount();
-  let copyCount = this.writer.getCopyCount();
-  if (this.isDryRun) {
-    ret.push("Pretended to");
+    (this.logger || console).log(this.logFinished());
+    debug("Finished writing templates.");
   }
-  if (copyCount) {
+
+  logFinished() {
+    if (!this.writer) {
+      throw new Error(
+        "Did you call Eleventy.init to create the TemplateWriter instance? Hint: you probably didn’t."
+      );
+    }
+
+    let ret = [];
+
+    let writeCount = this.writer.getWriteCount();
+    let copyCount = this.writer.getCopyCount();
+    if (this.isDryRun) {
+      ret.push("Pretended to");
+    }
+    if (copyCount) {
+      ret.push(
+        `${this.isDryRun ? "Copy" : "Copied"} ${copyCount} ${simplePlural(
+          copyCount,
+          "item",
+          "items"
+        )} and`
+      );
+    }
     ret.push(
-      `${this.isDryRun ? "Copy" : "Copied"} ${copyCount} ${simplePlural(
-        copyCount,
-        "item",
-        "items"
-      )} and`
+      `${this.isDryRun ? "Process" : "Processed"} ${writeCount} ${simplePlural(
+        writeCount,
+        "file",
+        "files"
+      )}`
     );
+
+    let time = ((new Date() - this.start) / 1000).toFixed(2);
+    ret.push(`in ${time} ${simplePlural(time, "second", "seconds")}`);
+
+    if (writeCount >= 10) {
+      ret.push(`(${((time * 1000) / writeCount).toFixed(1)}ms each)`);
+    }
+
+    return ret.join(" ");
   }
-  ret.push(
-    `${this.isDryRun ? "Process" : "Processed"} ${writeCount} ${simplePlural(
-      writeCount,
-      "file",
-      "files"
-    )}`
-  );
-
-  let time = ((new Date() - this.start) / 1000).toFixed(2);
-  ret.push(`in ${time} ${simplePlural(time, "second", "seconds")}`);
-
-  if (writeCount >= 10) {
-    ret.push(`(${((time * 1000) / writeCount).toFixed(1)}ms each)`);
-  }
 
-  return ret.join(" ");
-};
-
-Eleventy.prototype.init = async function() {
-  let formats = this.formatsOverride || this.config.templateFormats;
-  this.eleventyFiles = new EleventyFiles(
-    this.input,
-    this.outputDir,
-    formats,
-    this.isPassthroughAll
-  );
-  this.eleventyFiles.init();
-
-  this.templateData = new TemplateData(this.inputDir);
-  this.eleventyFiles.setTemplateData(this.templateData);
-
-  this.writer = new TemplateWriter(
-    this.input,
-    this.outputDir,
-    formats,
-    this.templateData,
-    this.isPassthroughAll
-  );
-
-  this.writer.setEleventyFiles(this.eleventyFiles);
-
-  // TODO maybe isVerbose -> console.log?
-  debug(`Directories:
+  async init() {
+    let formats = this.formatsOverride || this.config.templateFormats;
+    this.eleventyFiles = new EleventyFiles(
+      this.input,
+      this.outputDir,
+      formats,
+      this.isPassthroughAll
+    );
+    this.eleventyFiles.init();
+
+    this.templateData = new TemplateData(this.inputDir);
+    this.eleventyFiles.setTemplateData(this.templateData);
+
+    this.writer = new TemplateWriter(
+      this.input,
+      this.outputDir,
+      formats,
+      this.templateData,
+      this.isPassthroughAll
+    );
+
+    this.writer.setEleventyFiles(this.eleventyFiles);
+
+    // TODO maybe isVerbose -> console.log?
+    debug(`Directories:
 Input: ${this.inputDir}
 Data: ${this.templateData.getDataDir()}
 Includes: ${this.eleventyFiles.getIncludesDir()}
 Output: ${this.outputDir}
 Template Formats: ${formats.join(",")}`);
 
-  this.writer.setVerboseOutput(this.isVerbose);
-  this.writer.setDryRun(this.isDryRun);
+    this.writer.setVerboseOutput(this.isVerbose);
+    this.writer.setDryRun(this.isDryRun);
 
-  return this.templateData.cacheData();
-};
+    return this.templateData.cacheData();
+  }
 
-Eleventy.prototype.setIsDebug = function(isDebug) {
-  this.isDebug = !!isDebug;
-};
+  setIsDebug(isDebug) {
+    this.isDebug = !!isDebug;
+  }
 
-Eleventy.prototype.setIsVerbose = function(isVerbose) {
-  this.isVerbose = !!isVerbose;
+  setIsVerbose(isVerbose) {
+    this.isVerbose = !!isVerbose;
 
-  if (this.writer) {
-    this.writer.setVerboseOutput(this.isVerbose);
-  }
-  if (bench) {
-    bench.setVerboseOutput(this.isVerbose);
+    if (this.writer) {
+      this.writer.setVerboseOutput(this.isVerbose);
+    }
+    if (bench) {
+      bench.setVerboseOutput(this.isVerbose);
+    }
   }
-};
 
-Eleventy.prototype.setFormats = function(formats) {
-  if (formats && formats !== "*") {
-    this.formatsOverride = formats.split(",");
+  setFormats(formats) {
+    if (formats && formats !== "*") {
+      this.formatsOverride = formats.split(",");
+    }
   }
-};
 
-Eleventy.prototype.getVersion = function() {
-  return require("../package.json").version;
-};
+  getVersion() {
+    return require("../package.json").version;
+  }
 
-Eleventy.prototype.getHelp = function() {
-  return `usage: eleventy
+  getHelp() {
+    return `usage: eleventy
        eleventy --input=. --output=./_site
        eleventy --serve
 
@@ -220,218 +226,215 @@ Arguments:
      --dryrun
        Don’t write any files. Useful with \`DEBUG=Eleventy* npx eleventy\`
      --help`;
-};
-
-Eleventy.prototype.resetConfig = function() {
-  config.reset();
+  }
 
-  this.config = config.getConfig();
-  this.eleventyServe.updateConfig(this.config);
-};
+  resetConfig() {
+    config.reset();
 
-Eleventy.prototype._watch = async function(path) {
-  if (this.active) {
-    this.queuedToRun = path;
-    return;
+    this.config = config.getConfig();
+    this.eleventyServe.updateConfig(this.config);
   }
 
-  this.active = true;
+  async _watch(path) {
+    if (this.active) {
+      this.queuedToRun = path;
+      return;
+    }
 
-  let localProjectConfigPath = config.getLocalProjectConfigFile();
-  // reset and reload global configuration :O
-  if (path === localProjectConfigPath) {
-    this.resetConfig();
-  }
-  config.resetOnWatch();
+    this.active = true;
 
-  await this.restart();
-  this.watchTargets.clearDependencyRequireCache();
+    let localProjectConfigPath = config.getLocalProjectConfigFile();
+    // reset and reload global configuration :O
+    if (path === localProjectConfigPath) {
+      this.resetConfig();
+    }
+    config.resetOnWatch();
 
-  await this.write();
+    await this.restart();
+    this.watchTargets.clearDependencyRequireCache();
 
-  this.watchTargets.reset();
-  await this._initWatchDependencies();
+    await this.write();
 
-  // Add new deps to chokidar
-  this.watcher.add(this.watchTargets.getNewTargetsSinceLastReset());
+    this.watchTargets.reset();
+    await this._initWatchDependencies();
 
-  let isInclude =
-    path && TemplatePath.contains(path, this.eleventyFiles.getIncludesDir());
-  this.eleventyServe.reload(path, isInclude);
+    // Add new deps to chokidar
+    this.watcher.add(this.watchTargets.getNewTargetsSinceLastReset());
 
-  this.active = false;
+    let isInclude =
+      path && TemplatePath.contains(path, this.eleventyFiles.getIncludesDir());
+    this.eleventyServe.reload(path, isInclude);
 
-  if (this.queuedToRun) {
-    console.log("You saved while Eleventy was running, let’s run again.");
-    this.queuedToRun = false;
-    await this._watch(this.queuedToRun);
-  } else {
-    console.log("Watching…");
+    this.active = false;
+
+    if (this.queuedToRun) {
+      console.log("You saved while Eleventy was running, let’s run again.");
+      this.queuedToRun = false;
+      await this._watch(this.queuedToRun);
+    } else {
+      console.log("Watching…");
+    }
   }
-};
 
-Eleventy.prototype.getWatcher = function() {
-  return this.watcher;
-};
+  get watcherBench() {
+    return bench.get("Watcher");
+  }
 
-Eleventy.prototype.initWatch = async function() {
-  this.watchTargets.add(this.eleventyFiles.getGlobWatcherFiles());
+  async initWatch() {
+    this.watchTargets.add(this.eleventyFiles.getGlobWatcherFiles());
 
-  // Watch the local project config file
-  this.watchTargets.add(config.getLocalProjectConfigFile());
+    // Watch the local project config file
+    this.watchTargets.add(config.getLocalProjectConfigFile());
 
-  // Template and Directory Data Files
-  this.watchTargets.add(
-    await this.eleventyFiles.getGlobWatcherTemplateDataFiles()
-  );
+    // Template and Directory Data Files
+    this.watchTargets.add(
+      await this.eleventyFiles.getGlobWatcherTemplateDataFiles()
+    );
 
-  if (!this.watcherBench) {
-    this.watcherBench = bench.get("Watcher");
-  }
-  let benchmark = this.watcherBench.get(
-    "Watching JavaScript Dependencies (disable with `eleventyConfig.setWatchJavaScriptDependencies(false)`)"
-  );
-  benchmark.before();
-  await this._initWatchDependencies();
-  benchmark.after();
-};
-
-Eleventy.prototype._initWatchDependencies = async function() {
-  if (!this.watchTargets.watchJavaScriptDependencies) {
-    return;
+    let benchmark = this.watcherBench.get(
+      "Watching JavaScript Dependencies (disable with `eleventyConfig.setWatchJavaScriptDependencies(false)`)"
+    );
+    benchmark.before();
+    await this._initWatchDependencies();
+    benchmark.after();
   }
 
-  let dataDir = this.templateData.getDataDir();
-  function filterOutGlobalDataFiles(path) {
-    return !dataDir || path.indexOf(dataDir) === -1;
-  }
+  async _initWatchDependencies() {
+    if (!this.watchTargets.watchJavaScriptDependencies) {
+      return;
+    }
 
-  // Template files .11ty.js
-  this.watchTargets.addDependencies(this.eleventyFiles.getWatchPathCache());
+    let dataDir = this.templateData.getDataDir();
+    function filterOutGlobalDataFiles(path) {
+      return !dataDir || path.indexOf(dataDir) === -1;
+    }
 
-  // Config file dependencies
-  this.watchTargets.addDependencies(
-    config.getLocalProjectConfigFile(),
-    filterOutGlobalDataFiles.bind(this)
-  );
+    // Template files .11ty.js
+    this.watchTargets.addDependencies(this.eleventyFiles.getWatchPathCache());
+
+    // Config file dependencies
+    this.watchTargets.addDependencies(
+      config.getLocalProjectConfigFile(),
+      filterOutGlobalDataFiles.bind(this)
+    );
 
-  // Deps from Global Data (that aren’t in the global data directory, everything is watched there)
-  this.watchTargets.addDependencies(
-    this.templateData.getWatchPathCache(),
-    filterOutGlobalDataFiles.bind(this)
-  );
+    // Deps from Global Data (that aren’t in the global data directory, everything is watched there)
+    this.watchTargets.addDependencies(
+      this.templateData.getWatchPathCache(),
+      filterOutGlobalDataFiles.bind(this)
+    );
 
-  this.watchTargets.addDependencies(
-    await this.eleventyFiles.getWatcherTemplateJavaScriptDataFiles()
-  );
-};
+    this.watchTargets.addDependencies(
+      await this.eleventyFiles.getWatcherTemplateJavaScriptDataFiles()
+    );
+  }
 
-Eleventy.prototype.getWatchedFiles = async function() {
-  return this.watchTargets.getTargets();
-};
+  async getWatchedFiles() {
+    return this.watchTargets.getTargets();
+  }
 
-Eleventy.prototype.watch = async function() {
-  this.watcherBench = bench.get("Watcher");
-  this.watcherBench.setMinimumThresholdMs(500);
-  this.watcherBench.reset();
+  async watch() {
+    this.watcherBench.setMinimumThresholdMs(500);
+    this.watcherBench.reset();
 
-  const chokidar = require("chokidar");
+    const chokidar = require("chokidar");
 
-  this.active = false;
-  this.queuedToRun = false;
+    this.active = false;
+    this.queuedToRun = false;
 
-  // Note that watching indirectly depends on this for fetching dependencies from JS files
-  // See: TemplateWriter:pathCache and EleventyWatchTargets
-  await this.write();
+    // Note that watching indirectly depends on this for fetching dependencies from JS files
+    // See: TemplateWriter:pathCache and EleventyWatchTargets
+    await this.write();
 
-  await this.initWatch();
+    await this.initWatch();
 
-  // TODO improve unwatching if JS dependencies are removed (or files are deleted)
-  let rawFiles = await this.getWatchedFiles();
-  debug("Watching for changes to: %o", rawFiles);
+    // TODO improve unwatching if JS dependencies are removed (or files are deleted)
+    let rawFiles = await this.getWatchedFiles();
+    debug("Watching for changes to: %o", rawFiles);
 
-  let ignores = this.eleventyFiles.getGlobWatcherIgnores();
-  debug("Watching but ignoring changes to: %o", ignores);
+    let ignores = this.eleventyFiles.getGlobWatcherIgnores();
+    debug("Watching but ignoring changes to: %o", ignores);
 
-  let watcher = chokidar.watch(rawFiles, {
-    ignored: ignores,
-    ignoreInitial: true
-  });
+    let watcher = chokidar.watch(rawFiles, {
+      ignored: ignores,
+      ignoreInitial: true
+    });
 
-  this.watcherBench.finish("Initialize --watch", 10, this.isVerbose);
+    this.watcherBench.finish("Initialize --watch", 10, this.isVerbose);
 
-  console.log("Watching…");
+    console.log("Watching…");
 
-  this.watcher = watcher;
+    this.watcher = watcher;
 
-  async function watchRun(path) {
-    try {
-      await this._watch(path);
-    } catch (e) {
-      EleventyErrorHandler.fatal(e, "Eleventy fatal watch error");
-      watcher.close();
+    async function watchRun(path) {
+      try {
+        await this._watch(path);
+      } catch (e) {
+        EleventyErrorHandler.fatal(e, "Eleventy fatal watch error");
+        watcher.close();
+      }
     }
-  }
 
-  watcher.on("change", async path => {
-    console.log("File changed:", path);
-    await watchRun.call(this, path);
-  });
-
-  watcher.on("add", async path => {
-    console.log("File added:", path);
-    await watchRun.call(this, path);
-  });
-
-  process.on(
-    "SIGINT",
-    function() {
-      debug("Cleaning up chokidar and browsersync (if exists) instances.");
-      this.eleventyServe.close();
-      this.watcher.close();
-      process.exit();
-    }.bind(this)
-  );
-};
-
-Eleventy.prototype.serve = function(port) {
-  this.eleventyServe.serve(port);
-};
-
-/* For testing */
-Eleventy.prototype.setLogger = function(logger) {
-  this.logger = logger;
-};
-
-Eleventy.prototype.write = async function() {
-  let ret;
-  if (this.logger) {
-    EleventyErrorHandler.logger = this.logger;
+    watcher.on("change", async path => {
+      console.log("File changed:", path);
+      await watchRun.call(this, path);
+    });
+
+    watcher.on("add", async path => {
+      console.log("File added:", path);
+      await watchRun.call(this, path);
+    });
+
+    process.on(
+      "SIGINT",
+      function() {
+        debug("Cleaning up chokidar and browsersync (if exists) instances.");
+        this.eleventyServe.close();
+        this.watcher.close();
+        process.exit();
+      }.bind(this)
+    );
   }
 
-  try {
-    let promise = this.writer.write();
+  serve(port) {
+    this.eleventyServe.serve(port);
+  }
 
-    ret = await promise;
-  } catch (e) {
-    EleventyErrorHandler.initialMessage(
-      "Problem writing Eleventy templates",
-      "error",
-      "red"
-    );
-    EleventyErrorHandler.fatal(e);
+  /* For testing */
+  setLogger(logger) {
+    this.logger = logger;
   }
 
-  this.finish();
+  async write() {
+    let ret;
+    if (this.logger) {
+      EleventyErrorHandler.logger = this.logger;
+    }
+
+    try {
+      let promise = this.writer.write();
+
+      ret = await promise;
+    } catch (e) {
+      EleventyErrorHandler.initialMessage(
+        "Problem writing Eleventy templates",
+        "error",
+        "red"
+      );
+      EleventyErrorHandler.fatal(e);
+    }
+
+    this.finish();
 
-  debug(`
+    debug(`
 Getting frustrated? Have a suggestion/feature request/feedback?
 I want to hear it! Open an issue: https://github.com/11ty/eleventy/issues/new`);
 
-  // unset the logger
-  EleventyErrorHandler.logger = undefined;
+    // unset the logger
+    EleventyErrorHandler.logger = undefined;
 
-  return ret;
-};
+    return ret;
+  }
+}
 
 module.exports = Eleventy;