REST server + JavaScript-heavy client was the principle I've followed in my recent work.
REST server was implemented in node.js + Express + MongoDB (very good writing performance) + Mongoose ODM (great for modelling data, validations included) + CoffeeScript (I'd go ES2015 now instead) which worked well for me. Node.js might be relatively young compared to other possible server-side technologies, but it made it possible for me to write solid API with payments integrated.
I've used Ember.js as JavaScript framework and most of the application logic was executed in the browser. I've used SASS (SCSS specifically) for CSS pre-processing.
Ember is mature framework backed by strong community. It is very powerful framework with lots of work being done recently focused on performance, like brand new Glimmer rendering engine (inspired by React).
Ember Core Team is in process of developing FastBoot, which let's you to execute your JavaScript Ember logic on server-side (node.js specifically) and send pre-rendered HTML of your application (which would normally be run in browser) to user. It is great for SEO and user experience as he doesn't wait so long for page to be displayed.
Ember CLI is great tool that helps you to organise your code and it did well to scale with growing codebase. Ember has also it's own addon ecosystem and you can choose from variety of Ember Addons. You can easily grab Bootstrap (in my case) or Foundation and add it to your app.
Not to serve everything via Express, I've chosen to use nginx for serving images and JavaScript-heavy client. Using nginx proxy was helpful in my case:
upstream app_appName.com {
# replace 0.0.0.0 with your IP address and 1000 with your port of node HTTP server
server 0.0.0.0:1000;
keepalive 8;
}
server {
listen 80 default_server;
listen [::]:80 default_server ipv6only=on;
client_max_body_size 32M;
access_log /var/log/nginx/appName.access.log;
error_log /var/log/nginx/appName.error.log;
server_name appName.com appName;
location / {
# frontend assets path
root /var/www/html;
index index.html;
# to handle Ember routing
try_files $uri $uri/ /index.html?/$request_uri;
}
location /i/ {
alias /var/i/img/;
}
location /api/v1/ {
proxy_pass http://app_appName.com;
proxy_next_upstream error timeout invalid_header http_500 http_502
http_503 http_504;
proxy_redirect off;
proxy_buffering off;
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
}
}
Pro: I love the separation of API & client. Smart people say this is
the way to go. Great in theory. Seems cutting-edge and exciting.
I can say it's also great in practice. Another advantage of separating REST API is that you can re-use it later for another applications. In perfect world you should be able to use the same REST API not only for webpage, but also for mobile applications if you'd decide to write one.
Con: Not much precedent. Not many examples of this done well. Public
examples (twitter.com) feel sluggish & are even switching away from
this approach.
Things look different now. There are lots of examples of doing REST API + many clients consuming it.