diff --git a/socketio/package.json b/socketio/package.json
new file mode 100644
index 0000000..2aafb85
--- /dev/null
+++ b/socketio/package.json
@@ -0,0 +1,17 @@
+{
+ "name": "socket-io-example",
+ "version": "1.0.0",
+ "description": "",
+ "main": "src/index.js",
+ "scripts": {
+ "start": "nodemon src/index.js"
+ },
+ "dependencies": {
+ "express": "4.17.1",
+ "socket.io": "2.3.0"
+ },
+ "devDependencies": {
+ "nodemon": "1.18.4"
+ },
+ "keywords": []
+}
\ No newline at end of file
diff --git a/socketio/src/index.js b/socketio/src/index.js
new file mode 100644
index 0000000..bda082d
--- /dev/null
+++ b/socketio/src/index.js
@@ -0,0 +1,19 @@
+// @ts-check
+const path = require("path");
+const app = require("express")();
+const http = require("http").createServer(app);
+const io = require("socket.io")(http);
+
+const port = Number(process.env.PORT) || 8080;
+
+app.get("/", function(_, res) {
+ res.sendFile(path.join(__dirname, "public", "index.html"));
+});
+
+http.listen(port, function() {
+ console.log(`listening on http://localhost:${port}`);
+});
+
+io.on("connect", socket => {
+ socket.on("message", message => io.send(message));
+});
diff --git a/socketio/src/public/index.html b/socketio/src/public/index.html
new file mode 100644
index 0000000..ffcfcb1
--- /dev/null
+++ b/socketio/src/public/index.html
@@ -0,0 +1,50 @@
+
+
+
+
+
+ Demo
+
+
+
+
+
+
+
+ Developer Tools のコンソール (Ctrl+Shift+J や Cmd+Opt+J) を開いて次のコードを実行する:
+
+ メッセージを送るためのコードの例:
+
io().send("こんにちは")
+
+
+ メッセージを受け取るためのコードの例:
+
io().on("message", message => { document.body.textContent = message; })
+
+
+