diff --git a/.gitignore b/.gitignore
index 2ccbe46..3d2bc62 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1 +1,2 @@
+/dist/
 /node_modules/
diff --git a/index.d.ts b/index.d.ts
deleted file mode 100644
index a5db288..0000000
--- a/index.d.ts
+++ /dev/null
@@ -1,56 +0,0 @@
-/// <reference types="node" />
-import { EventEmitter } from "events";
-declare type PortNumber = number;
-declare type PortName = string;
-declare type PinName = string;
-declare type DirectionMode = "in" | "out";
-declare type GPIOValue = 0 | 1;
-interface GPIOChangeEvent {
-    readonly value: GPIOValue;
-    readonly port: GPIOPort;
-}
-interface GPIOChangeEventHandler {
-    (event: GPIOChangeEvent): void;
-}
-export declare class GPIOAccess extends EventEmitter {
-    private readonly _ports;
-    onchange: GPIOChangeEventHandler | undefined;
-    constructor(ports?: GPIOPortMap);
-    get ports(): GPIOPortMap;
-    /**
-     * Unexport all exported GPIO ports.
-     */
-    unexportAll(): Promise<void>;
-}
-/**
- * Different from Web GPIO API specification.
- */
-export declare class GPIOPortMap extends Map<PortNumber, GPIOPort> {
-}
-export declare class GPIOPort extends EventEmitter {
-    private readonly _portNumber;
-    private readonly _pollingInterval;
-    private _direction;
-    private _exported;
-    private _value;
-    private _timeout;
-    onchange: GPIOChangeEventHandler | undefined;
-    constructor(portNumber: PortNumber);
-    get portNumber(): PortNumber;
-    get portName(): PortName;
-    get pinName(): PinName;
-    get direction(): DirectionMode;
-    get exported(): boolean;
-    export(direction: DirectionMode): Promise<void>;
-    unexport(): Promise<void>;
-    read(): Promise<GPIOValue>;
-    write(value: GPIOValue): Promise<void>;
-}
-export declare class InvalidAccessError extends Error {
-    constructor(message: string);
-}
-export declare class OperationError extends Error {
-    constructor(message: string);
-}
-export declare function requestGPIOAccess(): Promise<GPIOAccess>;
-export {};
diff --git a/index.js b/index.js
deleted file mode 100644
index ef4fb1a..0000000
--- a/index.js
+++ /dev/null
@@ -1,169 +0,0 @@
-"use strict";
-Object.defineProperty(exports, "__esModule", { value: true });
-const events_1 = require("events");
-const fs_1 = require("fs");
-const path = require("path");
-/**
- * Interval of file system polling, in milliseconds.
- */
-const PollingInterval = 100;
-const SysfsGPIOPath = "/sys/class/gpio";
-const GPIOPortMapSizeMax = 1024;
-const Uint16Max = 65535;
-function parseUint16(string) {
-    const n = Number.parseInt(string, 10);
-    if (0 <= n && n <= Uint16Max)
-        return n;
-    else
-        throw new RangeError(`Must be between 0 and ${Uint16Max}.`);
-}
-class GPIOAccess extends events_1.EventEmitter {
-    constructor(ports) {
-        super();
-        this._ports = ports == null ? new GPIOPortMap() : ports;
-        this._ports.forEach(port => port.on("change", event => {
-            this.emit("change", event);
-        }));
-        this.on("change", (event) => {
-            if (this.onchange !== undefined)
-                this.onchange(event);
-        });
-    }
-    get ports() {
-        return this._ports;
-    }
-    /**
-     * Unexport all exported GPIO ports.
-     */
-    async unexportAll() {
-        await Promise.all([...this.ports.values()].map(port => port.exported ? port.unexport() : undefined));
-    }
-}
-exports.GPIOAccess = GPIOAccess;
-/**
- * Different from Web GPIO API specification.
- */
-class GPIOPortMap extends Map {
-}
-exports.GPIOPortMap = GPIOPortMap;
-class GPIOPort extends events_1.EventEmitter {
-    constructor(portNumber) {
-        super();
-        this._portNumber = parseUint16(portNumber.toString());
-        this._pollingInterval = PollingInterval;
-        this._direction = new OperationError("Unknown direction.");
-        this._exported = new OperationError("Unknown export.");
-        this.on("change", (event) => {
-            if (this.onchange !== undefined)
-                this.onchange(event);
-        });
-    }
-    get portNumber() {
-        return this._portNumber;
-    }
-    get portName() {
-        return `gpio${this.portNumber}`;
-    }
-    get pinName() {
-        // NOTE: Unknown pinName.
-        return "";
-    }
-    get direction() {
-        if (this._direction instanceof OperationError)
-            throw this._direction;
-        return this._direction;
-    }
-    get exported() {
-        if (this._exported instanceof OperationError)
-            throw this._exported;
-        return this._exported;
-    }
-    async export(direction) {
-        if (!/^(in|out)$/.test(direction)) {
-            throw new InvalidAccessError(`Must be "in" or "out".`);
-        }
-        try {
-            await fs_1.promises.access(path.join(SysfsGPIOPath, this.portName));
-            this._exported = true;
-        }
-        catch {
-            this._exported = false;
-        }
-        try {
-            clearInterval(this._timeout);
-            if (!this.exported) {
-                await fs_1.promises.writeFile(path.join(SysfsGPIOPath, "export"), String(this.portNumber));
-            }
-            await fs_1.promises.writeFile(path.join(SysfsGPIOPath, this.portName, "direction"), direction);
-            if (direction === "in") {
-                this._timeout = setInterval(this.read.bind(this), this._pollingInterval);
-            }
-        }
-        catch (error) {
-            throw new OperationError(error);
-        }
-        this._direction = direction;
-        this._exported = true;
-    }
-    async unexport() {
-        clearInterval(this._timeout);
-        try {
-            await fs_1.promises.writeFile(path.join(SysfsGPIOPath, "unexport"), String(this.portNumber));
-        }
-        catch (error) {
-            throw new OperationError(error);
-        }
-        this._exported = false;
-    }
-    async read() {
-        if (!(this.exported && this.direction === "in")) {
-            throw new InvalidAccessError(`The exported must be true and value of direction must be "in".`);
-        }
-        try {
-            const buffer = await fs_1.promises.readFile(path.join(SysfsGPIOPath, this.portName, "value"));
-            const value = parseUint16(buffer.toString());
-            if (this._value !== value) {
-                this._value = value;
-                this.emit("change", { value, port: this });
-            }
-            return value;
-        }
-        catch (error) {
-            throw new OperationError(error);
-        }
-    }
-    async write(value) {
-        if (!(this.exported && this.direction === "out")) {
-            throw new InvalidAccessError(`The exported must be true and value of direction must be "out".`);
-        }
-        try {
-            await fs_1.promises.writeFile(path.join(SysfsGPIOPath, this.portName, "value"), parseUint16(value.toString()).toString());
-        }
-        catch (error) {
-            throw new OperationError(error);
-        }
-    }
-}
-exports.GPIOPort = GPIOPort;
-class InvalidAccessError extends Error {
-    constructor(message) {
-        super(message);
-        this.name = this.constructor.name;
-    }
-}
-exports.InvalidAccessError = InvalidAccessError;
-class OperationError extends Error {
-    constructor(message) {
-        super(message);
-        this.name = this.constructor.name;
-    }
-}
-exports.OperationError = OperationError;
-async function requestGPIOAccess() {
-    const ports = new GPIOPortMap([...Array(GPIOPortMapSizeMax).keys()].map(portNumber => [
-        portNumber,
-        new GPIOPort(portNumber)
-    ]));
-    return new GPIOAccess(ports);
-}
-exports.requestGPIOAccess = requestGPIOAccess;
diff --git a/package.json b/package.json
index 2007bd0..18b8c9c 100644
--- a/package.json
+++ b/package.json
@@ -2,7 +2,11 @@
   "name": "node-web-gpio",
   "version": "1.0.0",
   "description": "GPIO access with Node.js",
-  "main": "index.js",
+  "main": "dist/index.js",
+  "types": "dist/index.d.ts",
+  "files": [
+    "dist/*"
+  ],
   "repository": {
     "type": "git",
     "url": "https://github.com/chirimen-oh/node-web-gpio.git"
@@ -14,7 +18,8 @@
     "typescript": "^4.0.2"
   },
   "scripts": {
-    "build": "tsc"
+    "build": "tsc",
+    "prepublish": "rm -rf dist && yarn build"
   },
   "keywords": [
     "gpio",
diff --git a/tsconfig.json b/tsconfig.json
index 71ed46f..2c499bc 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -1,5 +1,6 @@
 {
   "compilerOptions": {
+    "outDir": "dist",
     "target": "esnext",
     "module": "commonjs",
     "moduleResolution": "node",