fix broken path in chat example in windows

std/node/_fs/_fs_exists.ts

@@ -0,0 +1,34 @@
+// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+
+type ExitsCallback = (exists: boolean) => void;
+
+/* Deprecated in node api */
+
+export function exists(path: string, callback: ExitsCallback): void {
+  new Promise(async (resolve, reject) => {
+    try {
+      await Deno.lstat(path);
+      resolve();
+    } catch (err) {
+      reject(err);
+    }
+  })
+    .then(() => {
+      callback(true);
+    })
+    .catch(() => {
+      callback(false);
+    });
+}
+
+export function existsSync(path: string): boolean {
+  try {
+    Deno.lstatSync(path);
+    return true;
+  } catch (err) {
+    if (err instanceof Deno.errors.NotFound) {
+      return false;
+    }
+    throw err;
+  }
+}

std/node/_fs/_fs_exists_test.ts

@@ -0,0 +1,28 @@
+// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+
+import { assertEquals } from "../../testing/asserts.ts";
+import { exists, existsSync } from "./_fs_exists.ts";
+import * as path from "../../path/mod.ts";
+
+const { test } = Deno;
+
+const testAvailableData = path.resolve(path.join("testdata", "hello.txt"));
+const testNotAvailableData = path.resolve(
+  path.join("testdata", "notAvailable.txt")
+);
+
+test(async function existsFile() {
+  const availableFile = await new Promise((resolve, reject) => {
+    exists(testAvailableData, (exists: boolean) => resolve(exists));
+  });
+  const notAvailableFile = await new Promise((resolve, reject) => {
+    exists(testNotAvailableData, (exists: boolean) => resolve(exists));
+  });
+  assertEquals(availableFile, true);
+  assertEquals(notAvailableFile, false);
+});
+
+test(function existsSyncFile() {
+  assertEquals(existsSync(testAvailableData), true);
+  assertEquals(existsSync(testNotAvailableData), false);
+});

std/node/_fs/_fs_mkdir.ts

@@ -0,0 +1,73 @@
+// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+import { CallbackWithError } from "./_fs_common.ts";
+
+type Path = string; // TODO path can also be a Buffer or URL.
+type MkdirOptions =
+  | { recursive?: boolean; mode?: number | undefined }
+  | number
+  | boolean;
+
+export function mkdir(
+  path: Path,
+  options?: MkdirOptions | CallbackWithError,
+  callback?: CallbackWithError
+): void {
+  let mode: number = 0o777;
+  let recursive: boolean = false;
+
+  if (typeof options == "function") {
+    callback == options;
+  } else if (typeof options === "number") {
+    mode = options;
+  } else if (typeof options === "boolean") {
+    recursive = options;
+  } else if (options) {
+    if (options.recursive !== undefined) recursive = options.recursive;
+    if (options.mode !== undefined) mode = options.mode;
+  }
+  if (typeof recursive !== "boolean")
+    throw new Deno.errors.InvalidData(
+      "invalid recursive option , must be a boolean"
+    );
+  new Promise(async (resolve, reject) => {
+    try {
+      await Deno.mkdir(path, recursive, mode);
+      resolve();
+    } catch (err) {
+      reject(err);
+    }
+  })
+    .then(() => {
+      if (callback && typeof callback == "function") {
+        callback();
+      }
+    })
+    .catch((err) => {
+      if (callback && typeof callback == "function") {
+        callback(err);
+      }
+    });
+}
+
+export function mkdirSync(path: Path, options?: MkdirOptions): void {
+  let mode: number = 0o777;
+  let recursive: boolean = false;
+
+  if (typeof options === "number") {
+    mode = options;
+  } else if (typeof options === "boolean") {
+    recursive = options;
+  } else if (options) {
+    if (options.recursive !== undefined) recursive = options.recursive;
+    if (options.mode !== undefined) mode = options.mode;
+  }
+  if (typeof recursive !== "boolean")
+    throw new Deno.errors.InvalidData(
+      "invalid recursive option , must be a boolean"
+    );
+  try {
+    Deno.mkdirSync(path, recursive, mode);
+  } catch (err) {
+    throw err;
+  }
+}

std/node/fs.ts

@@ -8,6 +8,8 @@ import { close, closeSync } from "./_fs/_fs_close.ts";
 import * as constants from "./_fs/_fs_constants.ts";
 import { readFile, readFileSync } from "./_fs/_fs_readFile.ts";
 import { readlink, readlinkSync } from "./_fs/_fs_readlink.ts";
+import { exists, existsSync } from "./_fs/_fs_exists.ts";
+import { mkdir, mkdirSync } from "./_fs/_fs_mkdir.ts";
 
 export {
   access,
@@ -21,8 +23,12 @@ export {
   close,
   closeSync,
   constants,
+  exists,
+  existsSync,
   readFile,
   readFileSync,
   readlink,
   readlinkSync,
+  mkdir,
+  mkdirSync,
 };