Why is 'message' undefined regarding connect-flash?

I'm building an express app where when a user completes a form; if successful, they will see an alert confirming their submission.

In my server.js file, I am declaring

var cookieParser = require("cookie-parser"),
session = require("express-session"),
flash = require("connect-flash"),
app = express();

Followed by:

app.use(cookieParser("keyboard cat"));
app.use(session({ 
    cookie: { maxAge: 60000 },
    secret: "keyboard cat" 
}));
app.use(flash());
require("./server/config/routes.js")(app);`

My routes file:

app.get("/", function(req, res){
    res.render("index", { message: req.flash("success") });
});

app.post("/sendMsg", function(req, res){
    mainController.sendMsg(req, res);
});

app.get("/sentSuccess", function(req, res){
    req.flash("success", "Thanks!");
    res.redirect("/");
});

Finally in my main.js file for jquery calls (I'm using SweetAlert for alert styling):

$(document).ready(function(){
if(message){
    var frm = document.getElementsByName('msgForm')[0];
    swal({
        title: "Sweet!",
        text: "Thanks",
        imageUrl: "javascripts/sweetalert/thumbs-up.jpg"
    });
    frm.reset();
}
});

The issue I'm hitting is Uncaught ReferenceError: message is not defined on the client-side console. I've read through https://www.npmjs.com/package/connect-flash and looked through the example at https://github.com/jaredhanson/connect-flash/tree/master/examples/express3 but I'm not sure why message is not being passed back.

Solution

Maybe, the problem is with the way your code is trying to access the message variable. As @Pushkin said message will be passed to the view and can't be as such referenced by the javascript.

You can try this (in case you are using jade as view engine)

    if message
      .script
        // your javascript or function()

So finally code looks like :

if message
    .script
        var frm = document.getElementsByName('msgForm')[0];
            swal({
                title: "Sweet!",
                text: "Thanks",
                imageUrl: "javascripts/sweetalert/thumbs-up.jpg"
            });
            frm.reset();

Now you will be able to access the message variable.

In case if using ejs the syntax is almost similar

<% if (message) { %>
 // Do something here..
<% } %>