Cannot embed EJS when piping a response - node.js

Question

So I thought I pipe an html file as a response, instead of res.render to get faster performance.
Instead of
res.render('form',{title:'Login',userField:'Username',passField:'Password',photo: photo});
I do
var path = 'views/form.ejs';
var stream = fs.createReadStream(path);
stream.pipe(res);
In form.ejs I have this <% include menu %> that is not working when responding with a pipe. In my browser I see <% include menu %>.
How should I fix this? Or is it caused by the fact that piping send the html file piece by piece, so it doesnt get to render and embed properly, so there is no solid solution ?
Thank you

Answer 1

The stream.pipe() method has absolutely no idea about any of your rendering needs.
res.render() is designed to expect a renderable template and a configured view engine. You can see this in the source code for express:
res.render calls app.render which calls view.render.
When you pass your result to stream.pipe there is absolutely nothing that will attempt to render properties in the way that res.render does.
You are also probably not gaining any "performance" simply by using pipes.
In short: you want to render your result, so use res.render().

Answer 2

just to add to the answer above... in cases pipe is wanted for a specifique view.
like duncanhall said, using '.ejs' your template engine is the only way to get your "ejs markers" to work, by calling res.render('view'). Plus as you probably specified in your code your views folder will be for ejs, it will try to hook all views in that folder so you can't use the same folder for html files or it'll crash with :
Error: Failed to lookup view "clubs" in views directory "...
So if you only used html with css and maybe some JS and pictures for a purely static page, you can make a special html folder in which your html files will sit.
Then use :
app.get('/', function(req, res) {
res.header("Access-Control-Allow-Origin", "*");
res.header("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept");
var clubs = fs.createReadStream(__dirname + '/html/clubs.html')
clubs.pipe(res);
});
for exemple, and yes then it'll improve IO performances if that route is heavily visited because chunks are going to be gunned the trigger-happy way!
Non-blocking IO, streams, long-polling and asynchronism are, after all, what makes Node efficient.
Cheers~

Answer 3

It's not a good idea to load templates from fs directly, maybe you can load it into memory before listen. For example:
const viewFoo = fs.readFileSync('./views/foo.html');
const templateFoo = ejs.compile(viewFoo);
// then in your handler:
res.end(templateFoo({ title:'Login' /* ... */ }));
If you want to use stream as data to render in ejs template,
you can try ejs-stream2.
For example:
const { compile } = require('ejs-stream2');
const template = compile('<div><%- contentStream %-></div>');
app.get('/', (req, res) => {
const stream = template({ contentStream: renderToNodeStream(<App/>);
stream.pipe(res);
})