Here you can easily test pushing data to browsers with Fanout. This page uses MQTT.js.
Initializing... 
This page is subscribed to the test topic, and will display the results below:
Open this page in a separate window to see how pushing from either window will cause both windows to receive the message.
This page is using the following JavaScript to subscribe to events:
// token limited to read/write of "test" topic
const token = "205124e8e4b1933e780226c95fb0bd0091965a03";
const client = mqtt.connect("wss://mqtt-poc.edgecompute.app/mqtt", {
reconnectPeriod: 0,
protocolVersion: 5,
username: "",
password: token
});
client.on("connect", () => {
client.subscribe("test", (err) => {
if (!err) {
console.log("subscribed");
}
});
});
client.on("message", (topic, message) => {
// message is Buffer
$('#output').text(message.toString());
});