This demonstrates how to use the Ethereum Whisper v6 API. It will also work with v5, but not between versions.
The example assumes that there is a running Whisper v6 node exposing an RPC interface at URL http://localhost:8545. For this, you can use geth with the folloing parameters:
$ geth <usual p2p flags> --shh --rpc --rpccorsdomain '*'
--shh is the option that enables Whisper for the node.
--rpc enables the HTTP RPC interface and --rplccorsdomain '*' will disable this annoying CORS verification in the browser. Needless to say, this is only acceptable because this is an example.
Then, clone this repository and download the dependencies:
$ npm install
Finally, start the example with:
$ npm run dev
The example should be started and the application will be available at http://localhost:8080.