Send JavaScript from Common Lisp to a browser.

First, we create a context object:

(defvar ctx (remote-js:make-context))

Then we start the WebSockets server:

(remote-js:start ctx)

Now, remote-js gives us a function that generates the HTML of a simple page that connects to this context and notifies it when it's connected. We write the HTML to ~/test.html:

(with-open-file (stream (merge-pathnames #p"test.html" (user-homedir-pathname))
                        :direction :output
                        :if-exists :supersede
                        :if-does-not-exist :create)
  (write-string (remote-js:html ctx) stream))

Open the file in your browser. Now you can do:

(remote-js:eval ctx "alert('hello!')")

And you will see the alert box pop up in your browser.

remote-js defines a function in the generated HTML, RemoteJS.send, which takes a string and sends it to the server. You can specify a callback for receiving messages like this:

(defvar ctx (remote-js:make-context
              :callback #'(lambda (message) (format t "Received: ~A~%" message))))

Then, start everything and generate the HTML file again:

(remote-js:start ctx)
(with-open-file (stream (merge-pathnames #p"test.html" (user-homedir-pathname))
                        :direction :output
                        :if-exists :supersede
                        :if-does-not-exist :create)
  (write-string (remote-js:html ctx) stream))

And open test.html in your browser.

Now you can send messages to the server like this:

CL-USER> (remote-js:eval ctx "RemoteJS.send('hi!')")
Received: hi!

Note: when a client connects to the server, it sends the string remote-js:+connected-message+.

The tests use trivial-open-browser, and running them will open your default browser to a temporary file.

Copyright (c) 2016 Fernando Borretti

Licensed under the MIT License.