Flash Message from ejs in Express 4
<p>I am trying to show a confirmation message before user deletes anything. I've tried following various related sources that I found in internet, but couldn't get them to work. I am using EJS template and Express 4.</p>

<p>app.js</p>

<pre><code>var express = require('express');
var path = require('path');
var favicon = require('serve-favicon');
var logger = require('morgan');
var cookieParser = require('cookie-parser');
var bodyParser = require('body-parser');

var routes = require('./routes/index');
var users = require('./routes/users');

var app = express();
var flash = require('connect-flash');
var session = require('express-session');

// view engine setup
app.set('views', path.join(__dirname, 'views'));
app.set('view engine', 'ejs');

app.use('/js', express.static(__dirname + '/node_modules/bootstrap/dist/js')); // redirect bootstrap JS
app.use('/css', express.static(__dirname + '/node_modules/bootstrap/dist/css')); // redirect CSS bootstrap


// uncomment after placing your favicon in /public
//app.use(favicon(__dirname + '/public/favicon.ico'));
app.use(logger('dev'));
app.use(cookieParser());
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: false }));
app.use(cookieParser());
app.use(require('stylus').middleware(path.join(__dirname, 'public')));
app.use(express.static(path.join(__dirname, 'public')));

app.use(session({ secret: 'zxcv' })); // session secret
app.use(flash()); // use connect-flash for flash messages stored in session

app.use('/', routes);
app.use('/users', users);

// catch 404 and forward to error handler
app.use(function (req, res, next) {
    var err = new Error('Not Found');
    err.status = 404;
    next(err);
});

// error handlers

// development error handler
// will print stacktrace
if (app.get('env') === 'development') {
    app.use(function (err, req, res, next) {
        res.status(err.status || 500);
        res.render('error', {
            message: err.message,
            error: err
        });
    });
}

// production error handler
// no stacktraces leaked to user
app.use(function (err, req, res, next) {
    res.status(err.status || 500);
    res.render('error', {
        message: err.message,
        error: {}
    });
});

app.listen(8000);
module.exports = app;
</code></pre>

<p>index.js</p>

<pre><code>var express = require('express');
var router = express.Router();

var searchModule = require('../crud_module/search.js');
var updateModule = require('../crud_module/update.js');
var deleteModule = require('../crud_module/delete.js');


/* GET home page. */
router.get('/', function (req, res) {
    res.render('index', { title: '' });
});

router.post('/search-results', function (req, res) {
    searchModule.search(req.body, function (data) {
        res.render('index', { title: '', results: data });
    });
});

router.post('/edit-data', function (req, res) {
    searchModule.searchById(req.body, function (data) {
        res.render('edit', { title: '', results: data });
    });
});

router.post('/save-changes', function (req, res) {
    if (req.body.change == "update") {
        updateModule.saveChanges(req.body, function (err) {
            if (err) {
                res.render('edit', { message: req.flash('Error', 'Error Occured') });

            } else {
                //req.flash('success', 'Your name was updated');
                res.render('edit', { message: req.flash('success', 'Data was updated')) });
            }
            res.redirect('/edit-data');
        });
    }
if (req.body.change == "delete") {
        deleteModule.deleteRecord(req.body, function (data) {
            res.render('edit', { title: 'Volume Tracker', confirmation: data });

        });
    }
});


module.exports = router;
</code></pre>

<p>edit.ejs</p>

<pre><code>&lt;!DOCTYPE html&gt;
&lt;html&gt;
&lt;head&gt;
    &lt;link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/css/bootstrap.min.css"&gt;
    &lt;link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/css/bootstrap-theme.min.css"&gt;
    &lt;link href="node_modules/popups/css/popupS.min.css" rel="stylesheet" /&gt;
    &lt;script type="text/javascript" src="https://gc.kis.scr.kaspersky-labs.com/5B1FA715-F8FF-784F-A4C9-0D867337CB3D/main.js" charset="UTF-8"&gt;&lt;/script&gt;&lt;script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.3/jquery.min.js"&gt;&lt;/script&gt;
    &lt;script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/js/bootstrap.min.js"&gt;&lt;/script&gt;
    &lt;script src="node_modules/elasticsearch/src/elasticsearch.angular.js"&gt;&lt;/script&gt;
    &lt;script src="node_modules/popups/dist/popupS.min.js"&gt;&lt;/script&gt;
    &lt;script language="javascript"&gt;

    &lt;/script&gt;
&lt;style type="text/css"&gt;


&lt;/style&gt;

&lt;/head&gt;

&lt;body&gt;
&lt;br&gt;

&lt;form action='/save-changes' method='post'&gt;
&lt;div class="container"&gt;



    &lt;% if(locals.results) { %&gt;
      &lt;table class="table table-bordered table-hover table-condensed"&gt; 
        &lt;tr&gt;
            &lt;th  bgcolor="silver"&gt;Term Key&lt;/th&gt;
            &lt;td&gt;
              &lt;input name="termKey"  value= "&lt;%= results[0]._source.termkey %&gt;" style="border:none; width:100%"/&gt;
            &lt;/td&gt;
          &lt;/tr&gt;

          &lt;tr&gt;
            &lt;th bgcolor="silver"&gt;Active&lt;/th&gt;
            &lt;td&gt;
              &lt;input name="active" value= "&lt;%= results[0]._source.active %&gt;" style="border:none; width:100%"/&gt;
            &lt;/td&gt;
          &lt;/tr&gt;

          &lt;tr&gt;
            &lt;th bgcolor="silver"&gt;Term Description&lt;/th&gt;
            &lt;td&gt;
              &lt;input name="termDescription" value= "&lt;%= results[0]._source.termdescription %&gt;" style="border:none; width:100%"/&gt;
            &lt;/td&gt;
          &lt;/tr&gt;


      &lt;/table&gt;  
      &lt;div align="center"&gt;
      &lt;button type="submit" class="btn btn-info" name="change" value="update"&gt; Save Changes &lt;/button&gt;
      &lt;button type="submit" class="btn btn-danger" name="change" value="delete"&gt; Delete Record &lt;/button&gt;
      &lt;/div&gt;


    &lt;% } %&gt;
    &lt;/form&gt;
    &lt;br&gt;

    &lt;/div&gt;

    &lt;/body&gt;
    &lt;/html&gt;
</code></pre>

<p>Here, when the user will click on the delete button, a confirmation message will be shown (here--> in index.js, I first tried showing confirmation message after user updates anything; which didn't work either). But whenever I try to include this: </p>

<pre><code>    &lt;% if (message.length &gt; 0) { %&gt;
            &lt;div class="alert alert-danger"&gt;&lt;%= message %&gt;&lt;/div&gt;
        &lt;% } %&gt;
in edit.ejs , I get error:
ReferenceError: 
    92|     &lt;/form&gt;
    93|     &lt;br&gt;
 &gt;&gt; 94|     &lt;% if (message.length &gt; 0) { %&gt;
    95|         &lt;div class="alert alert-danger"&gt;&lt;%= message %&gt;&lt;/div&gt;
    96|     &lt;% } %&gt;




 message is not defined
        at eval (eval at &lt;anonymous&gt; (\ElasticSearch\ES\VolumeTracker\VolumeTracker\node_modules\ejs\lib\ejs.js:495:12), &lt;anonymous&gt;:41:12)
    at Template.compile.returnedFn (\ElasticSearch\ES\VolumeTracker\VolumeTracker\node_modules\ejs\lib\ejs.js:524:17)
    at View.exports.renderFile [as engine] (\ElasticSearch\ES\VolumeTracker\VolumeTracker\node_modules\ejs\lib\ejs.js:378:31)
    at View.render (\ElasticSearch\ES\VolumeTracker\VolumeTracker\node_modules\express\lib\view.js:76:8)
    at Function.app.render (\ElasticSearch\ES\VolumeTracker\VolumeTracker\node_modules\express\lib\application.js:527:10)
    at ServerResponse.res.render (\ElasticSearch\ES\VolumeTracker\VolumeTracker\node_modules\express\lib\response.js:900:7)
    at \ElasticSearch\ES\VolumeTracker\VolumeTracker\routes\index.js:22:13
    at \ElasticSearch\ES\VolumeTracker\VolumeTracker\crud_module\search.js:45:9
    at tryCallOne (\ElasticSearch\ES\VolumeTracker\VolumeTracker\node_modules\elasticsearch\node_modules\promise\lib\core.js:37:12)
    at \ElasticSearch\ES\VolumeTracker\VolumeTracker\node_modules\elasticsearch\node_modules\promise\lib\core.js:123:15
</code></pre>