API to send requests externally to emit events through sockets

I'm using express-ws to perform socket routing. I want to create an API (mostly a POST API). On hitting the API, it should emit events through sockets.

app.ws('/echo', function(ws, req) {
    ws.on('message', function(msg) {
        ws.send("Hello World!");
    });
    ws.send("Testing something");
    console.log("Hello world!");
});

The above is my code and the code below is my browser code.

$(function() {
  var ws = new WebSocket("ws://localhost:3000/echo");

  ws.onopen = function() {
    console.log("Web Socket open!");
    //ws.send("Hi!");
  };
  ws.onerror = function(err) {
    console.log("Web socket error: " + err);
  };
  ws.onclose = function() {
    console.log("Web socket closing: ");
  };
  ws.onmessage = function(data) {
    console.log("Web socket receiving data: ");
    console.log(data.data)
  };
});

I can see that the browser is able to setup a connection. How can I externally hit this API? I cannot find any doc on whether it should be a GET request or a POST request and when I try the below code. I get the error message (ws is not defined).

app.get('/', function(req, res, next){
  console.log('get route');
  ws.send('message',"Hello world")
  res.end();
});

Note : I need this to be socket based and not a normal API.

via puneeth8994