ClojureScript: Up and Running

Chapter 10. Integration with Clojure

ClojureScript, as we have seen, is targeted primarily at web browsers. Although this makes it possible to design complete applications that run in a browser, it is even more powerful when combined with a web server running Clojure on the JVM. Clojure’s literal data structures provide a rich data format for communication between a client and server, and with a little care you can even share code between the two languages.

AJAX

In spite of its original definition, Asynchronous JavaScript and XML, AJAX has become a catch-all term for rich client applications running in web browsers, communicating with a web server. The Google Closure Library provides the goog.net.XhrIo class to support asynchronous HTTP requests to a server across many different browser implementations.

Here is a simple example function that performs an HTTP POST request to a server:

(ns example
  (:require [goog.net.XhrIo :as xhr]))

(defn receiver [event]
  (let [response (.-target event)]
    (.write js/document (.getResponseText response))))

(defn post [url content]
  (xhr/send url receiver "POST" content))

The goog.net.XhrIo/send function takes a URL, a callback function, a method name, and an optional request body. When the server responds to the request, it will invoke the callback function on an object from which you can retrieve the status code, headers, and response body sent by the server.

The goog.net.XhrIo class and the associated goog.net.XhrManager class provide many more options ...