Question

Is there a way to render template to a variable instead to output?

res.render('list.ejs', {
    posts: posts
});

something like this

var list = render('list.ejs', {
    posts: posts
});

Answer 1

The easiest way to do that is to pass a callback to res.render, in your example:

res.render('list.ejs', {posts: posts}, function(err, list){
  // 
});

But if you want to render partial templates in order to include them in another template you definitely should have a look at view partials.