Broadcast a basic event to all clients-CodePudding

How would I go about broadcasting alert("Hello World!"); on all clients currently avaible?
I have gone through these links:

And NONE of them helped. Can someone please help me?!

Solutions I have tried:

// Script.js:
var socket;

function onl oad(){
  socket = io();
}

function test(){
   socket.emit("broadcast");
}
socket.on('broadcast', function() {
    alert("Hello World!");
});

// index.js:
const express = require("express");
const socketio = require("socket.io");
const path = require("path");
const app = express();
const http = require("http");
const io2 = require("socket.io-client");

const directory = path.join(__dirname, "html");
const httpserver = http.Server(app);
const io = socketio(httpserver);

app.use(express.static(directory));
httpserver.listen(3000);

CodePudding user response：

To broadcast a message to all connected clients from your server, you do:

io.emit('bulletin', someMsg);

To listen for that message in the client, you do this:

socket.on('bulletin', someMsg => {
    console.log(someMsg);
});

The message name 'bulletin' can be anything you want it to be (any string that doesn't conflict with a built-in message name).

You cannot trigger a broadcast directly from the client. But, you can send the server a custom message that you design and have the server, upon receipt of that message, then do a broadcast to all connected clients.