snapshot of https://github.com/pion/webrtc.git (main, 2026-09-15; blobs > 131072B omitted)

examples/data-channels/jsfiddle/demo.css

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+/*
+    SPDX-FileCopyrightText: 2026 The Pion community <https://pion.ly>
+    SPDX-License-Identifier: MIT
+*/
+textarea {
+    width: 500px;
+    min-height: 75px;
+}

examples/data-channels/jsfiddle/demo.details

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+---
+# SPDX-FileCopyrightText: 2026 The Pion community <https://pion.ly>
+# SPDX-License-Identifier: MIT
+
+name: data-channels
+description: Example of using Pion WebRTC to communicate with a web browser using bi-direction DataChannels
+authors:
+  - Sean DuBois

examples/data-channels/jsfiddle/demo.html

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+<!--
+	SPDX-FileCopyrightText: 2026 The Pion community <https://pion.ly>
+	SPDX-License-Identifier: MIT
+-->
+Browser base64 Session Description<br />
+<textarea id="localSessionDescription" readonly="true"></textarea> <br />
+<button onclick="window.copySDP()">
+	Copy browser SDP to clipboard
+</button>
+<br />
+<br />
+
+Golang base64 Session Description<br />
+<textarea id="remoteSessionDescription"></textarea><br/>
+<button onclick="window.startSession()">Start Session</button><br />
+
+<br />
+
+Message<br />
+<textarea id="message">This is my DataChannel message!</textarea> <br/>
+<button onclick="window.sendMessage()">Send Message</button> <br />
+
+<br />
+Logs<br />
+<div id="logs"></div>

examples/data-channels/jsfiddle/demo.js

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+/* eslint-env browser */
+
+// SPDX-FileCopyrightText: 2026 The Pion community <https://pion.ly>
+// SPDX-License-Identifier: MIT
+
+const pc = new RTCPeerConnection({
+  iceServers: [
+    {
+      urls: 'stun:stun.l.google.com:19302'
+    }
+  ]
+})
+const log = msg => {
+  document.getElementById('logs').innerHTML += msg + '<br>'
+}
+
+const sendChannel = pc.createDataChannel('foo')
+sendChannel.onclose = () => console.log('sendChannel has closed')
+sendChannel.onopen = () => console.log('sendChannel has opened')
+sendChannel.onmessage = e => log(`Message from DataChannel '${sendChannel.label}' payload '${e.data}'`)
+
+pc.oniceconnectionstatechange = e => log(pc.iceConnectionState)
+pc.onicecandidate = event => {
+  if (event.candidate === null) {
+    document.getElementById('localSessionDescription').value = btoa(JSON.stringify(pc.localDescription))
+  }
+}
+
+pc.onnegotiationneeded = e =>
+  pc.createOffer().then(d => pc.setLocalDescription(d)).catch(log)
+
+window.sendMessage = () => {
+  const message = document.getElementById('message').value
+  if (message === '') {
+    return alert('Message must not be empty')
+  }
+
+  sendChannel.send(message)
+}
+
+window.startSession = () => {
+  const sd = document.getElementById('remoteSessionDescription').value
+  if (sd === '') {
+    return alert('Session Description must not be empty')
+  }
+
+  try {
+    pc.setRemoteDescription(JSON.parse(atob(sd)))
+  } catch (e) {
+    alert(e)
+  }
+}
+
+window.copySDP = () => {
+  const browserSDP = document.getElementById('localSessionDescription')
+
+  browserSDP.focus()
+  browserSDP.select()
+
+  try {
+    const successful = document.execCommand('copy')
+    const msg = successful ? 'successful' : 'unsuccessful'
+    log('Copying SDP was ' + msg)
+  } catch (err) {
+    log('Unable to copy SDP ' + err)
+  }
+}

examples/data-channels/jsfiddle/main.go

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+// SPDX-FileCopyrightText: 2026 The Pion community <https://pion.ly>
+// SPDX-License-Identifier: MIT
+
+//go:build js && wasm
+// +build js,wasm
+
+package main
+
+import (
+	"bufio"
+	"encoding/base64"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"os"
+	"strings"
+	"syscall/js"
+
+	"github.com/pion/webrtc/v4"
+)
+
+func main() {
+	// Configure and create a new PeerConnection.
+	config := webrtc.Configuration{
+		ICEServers: []webrtc.ICEServer{
+			{
+				URLs: []string{"stun:stun.l.google.com:19302"},
+			},
+		},
+	}
+	pc, err := webrtc.NewPeerConnection(config)
+	if err != nil {
+		handleError(err)
+	}
+
+	// Create DataChannel.
+	sendChannel, err := pc.CreateDataChannel("foo", nil)
+	if err != nil {
+		handleError(err)
+	}
+	sendChannel.OnClose(func() {
+		fmt.Println("sendChannel has closed")
+	})
+	sendChannel.OnClosing(func() {
+		fmt.Println("sendChannel is closing")
+	})
+	sendChannel.OnError(func(err error) {
+		fmt.Println("sendChannel error", err)
+	})
+	sendChannel.OnOpen(func() {
+		fmt.Println("sendChannel has opened")
+
+		candidatePair, err := pc.SCTP().Transport().ICETransport().GetSelectedCandidatePair()
+
+		fmt.Println(candidatePair)
+		fmt.Println(err)
+	})
+	sendChannel.OnMessage(func(msg webrtc.DataChannelMessage) {
+		log(fmt.Sprintf("Message from DataChannel %s payload %s", sendChannel.Label(), string(msg.Data)))
+	})
+
+	// Create offer
+	offer, err := pc.CreateOffer(nil)
+	if err != nil {
+		handleError(err)
+	}
+	if err := pc.SetLocalDescription(offer); err != nil {
+		handleError(err)
+	}
+
+	// Add handlers for setting up the connection.
+	pc.OnICEConnectionStateChange(func(state webrtc.ICEConnectionState) {
+		log(fmt.Sprint(state))
+	})
+	pc.OnICECandidate(func(candidate *webrtc.ICECandidate) {
+		if candidate != nil {
+			encodedDescr := encode(pc.LocalDescription())
+			el := getElementByID("localSessionDescription")
+			el.Set("value", encodedDescr)
+		}
+	})
+
+	// Set up global callbacks which will be triggered on button clicks.
+	js.Global().Set("sendMessage", js.FuncOf(func(_ js.Value, _ []js.Value) any {
+		go func() {
+			el := getElementByID("message")
+			message := el.Get("value").String()
+			if message == "" {
+				js.Global().Call("alert", "Message must not be empty")
+				return
+			}
+			if err := sendChannel.SendText(message); err != nil {
+				handleError(err)
+			}
+		}()
+		return js.Undefined()
+	}))
+	js.Global().Set("startSession", js.FuncOf(func(_ js.Value, _ []js.Value) any {
+		go func() {
+			el := getElementByID("remoteSessionDescription")
+			sd := el.Get("value").String()
+			if sd == "" {
+				js.Global().Call("alert", "Session Description must not be empty")
+				return
+			}
+
+			descr := webrtc.SessionDescription{}
+			decode(sd, &descr)
+			if err := pc.SetRemoteDescription(descr); err != nil {
+				handleError(err)
+			}
+		}()
+		return js.Undefined()
+	}))
+	js.Global().Set("copySDP", js.FuncOf(func(_ js.Value, _ []js.Value) any {
+		go func() {
+			defer func() {
+				if e := recover(); e != nil {
+					switch e := e.(type) {
+					case error:
+						handleError(e)
+					default:
+						handleError(fmt.Errorf("recovered with non-error value: (%T) %s", e, e))
+					}
+				}
+			}()
+
+			browserSDP := getElementByID("localSessionDescription")
+
+			browserSDP.Call("focus")
+			browserSDP.Call("select")
+
+			copyStatus := js.Global().Get("document").Call("execCommand", "copy")
+			if copyStatus.Bool() {
+				log("Copying SDP was successful")
+			} else {
+				log("Copying SDP was unsuccessful")
+			}
+		}()
+		return js.Undefined()
+	}))
+
+	// Stay alive
+	select {}
+}
+
+func log(msg string) {
+	el := getElementByID("logs")
+	el.Set("innerHTML", el.Get("innerHTML").String()+msg+"<br>")
+}
+
+func handleError(err error) {
+	log("Unexpected error. Check console.")
+	panic(err)
+}
+
+func getElementByID(id string) js.Value {
+	return js.Global().Get("document").Call("getElementById", id)
+}
+
+// Read from stdin until we get a newline
+func readUntilNewline() (in string) {
+	var err error
+
+	r := bufio.NewReader(os.Stdin)
+	for {
+		in, err = r.ReadString('\n')
+		if err != nil && !errors.Is(err, io.EOF) {
+			panic(err)
+		}
+
+		if in = strings.TrimSpace(in); len(in) > 0 {
+			break
+		}
+	}
+
+	fmt.Println("")
+	return
+}
+
+// JSON encode + base64 a SessionDescription
+func encode(obj *webrtc.SessionDescription) string {
+	b, err := json.Marshal(obj)
+	if err != nil {
+		panic(err)
+	}
+
+	return base64.StdEncoding.EncodeToString(b)
+}
+
+// Decode a base64 and unmarshal JSON into a SessionDescription
+func decode(in string, obj *webrtc.SessionDescription) {
+	b, err := base64.StdEncoding.DecodeString(in)
+	if err != nil {
+		panic(err)
+	}
+
+	if err = json.Unmarshal(b, obj); err != nil {
+		panic(err)
+	}
+}