'mode' can be a number or a string.

I realize this could be considered pedantic, but the typings do not even consistently use one or the other. Previously, certain functions assumed string, others assumed number. This way, you can use either.

node/node.d.ts

@@ -737,11 +737,17 @@ declare module "fs" {
     export function fchownSync(fd: string, uid: number, gid: number): void;
     export function lchown(path: string, uid: number, gid: number, callback?: Function): void;
     export function lchownSync(path: string, uid: number, gid: number): void;
+    export function chmod(path: string, mode: number, callback?: Function): void;
     export function chmod(path: string, mode: string, callback?: Function): void;
+    export function chmodSync(path: string, mode: number): void;
     export function chmodSync(path: string, mode: string): void;
+    export function fchmod(fd: string, mode: number, callback?: Function): void;
     export function fchmod(fd: string, mode: string, callback?: Function): void;
+    export function fchmodSync(fd: string, mode: number): void;
     export function fchmodSync(fd: string, mode: string): void;
+    export function lchmod(path: string, mode: number, callback?: Function): void;
     export function lchmod(path: string, mode: string, callback?: Function): void;
+    export function lchmodSync(path: string, mode: number): void;
     export function lchmodSync(path: string, mode: string): void;
     export function stat(path: string, callback?: (err: Error, stats: Stats) =>any): Stats;
     export function lstat(path: string, callback?: (err: Error, stats: Stats) =>any): Stats;
@@ -763,14 +769,18 @@ declare module "fs" {
     export function rmdir(path: string, callback?: Function): void;
     export function rmdirSync(path: string): void;
     export function mkdir(path: string, callback?: Function): void;
+    export function mkdir(path: string, mode: number, callback?: Function): void;
     export function mkdir(path: string, mode: string, callback?: Function): void;
+    export function mkdirSync(path: string, mode?: number): void;
     export function mkdirSync(path: string, mode?: string): void;
     export function readdir(path: string, callback?: (err: Error, files: string[]) => void): void;
     export function readdirSync(path: string): string[];
     export function close(fd: string, callback?: Function): void;
     export function closeSync(fd: string): void;
     export function open(path: string, flags: string, callback?: (err: Error, fd: string) => any): void;
+    export function open(path: string, flags: string, mode: number, callback?: (err: Error, fd: string) => any): void;
     export function open(path: string, flags: string, mode: string, callback?: (err: Error, fd: string) => any): void;
+    export function openSync(path: string, flags: string, mode?: number): void;
     export function openSync(path: string, flags: string, mode?: string): void;
     export function utimes(path: string, atime: number, mtime: number, callback?: Function): void;
     export function utimesSync(path: string, atime: number, mtime: number): void;
@@ -788,10 +798,14 @@ declare module "fs" {
     export function readFileSync(filename: string, options: { encoding?: string; flag?: string; }): any;
     export function writeFile(filename: string, data: any, callback?: (err: Error) => void): void;
     export function writeFile(filename: string, data: any, options: { encoding?: string; mode?: number; flag?: string; }, callback?: (err: Error) => void): void;
+    export function writeFile(filename: string, data: any, options: { encoding?: string; mode?: string; flag?: string; }, callback?: (err: Error) => void): void;
     export function writeFileSync(filename: string, data: any, options?: { encoding?: string; mode?: number; flag?: string; }): void;
+    export function writeFileSync(filename: string, data: any, options?: { encoding?: string; mode?: string; flag?: string; }): void;
     export function appendFile(filename: string, data: any, options: { encoding?: string; mode?: number; flag?: string; }, callback?: (err: Error) => void): void;
+    export function appendFile(filename: string, data: any, options: { encoding?: string; mode?: string; flag?: string; }, callback?: (err: Error) => void): void;
     export function appendFile(filename: string, data: any, callback?: (err: Error) => void): void;
     export function appendFileSync(filename: string, data: any, options?: { encoding?: string; mode?: number; flag?: string; }): void;
+    export function appendFileSync(filename: string, data: any, options?: { encoding?: string; mode?: string; flag?: string; }): void;
     export function watchFile(filename: string, listener: { curr: Stats; prev: Stats; }): void;
     export function watchFile(filename: string, options: { persistent?: boolean; interval?: number; }, listener: { curr: Stats; prev: Stats; }): void;
     export function unwatchFile(filename: string, listener?: Stats): void;
@@ -805,6 +819,13 @@ declare module "fs" {
         mode?: number;
         bufferSize?: number;
     }): ReadStream;
+    export function createReadStream(path: string, options?: {
+        flags?: string;
+        encoding?: string;
+        fd?: string;
+        mode?: string;
+        bufferSize?: number;
+    }): ReadStream;
     export function createWriteStream(path: string, options?: {
         flags?: string;
         encoding?: string;