NodeJS

Provides an Elixir API for calling Node.js functions.

Documentation

The docs can be found at https://hexdocs.pm/nodejs.

def deps do
  [
    {:nodejs, "~> 2.0"}
  ]
end

Add NodeJS to your Supervisor as a child, pointing the required path option at the directory containing your JavaScript modules.

supervisor(NodeJS, [[path: "/node_app_root", pool_size: 4]])

If the module exports a function directly, like this:

module.exports = (x) => x

You can call it like this:

NodeJS.call("echo", ["hello"]) #=> {:ok, "hello"}

There is also a call! form that throws on error instead of returning a tuple:

NodeJS.call!("echo", ["hello"]) #=> "hello"

If the module exports an object with named functions like:

exports.add = (a, b) => a + b
exports.sub = (a, b) => a - b

You can call them like this:

NodeJS.call({"math", :add}, [1, 2]) # => {:ok, 3}
NodeJS.call({"math", :sub}, [1, 2]) # => {:ok, -1}

In order to cope with Unicode character it is necessary to specify the binary option:

NodeJS.call("echo", ["’"], binary: true) # => {:ok, "’"}

Function arguments must be serializable to JSON.
Return values must be serializable to JSON. (Objects with circular references will definitely fail.)
Modules must be requested relative to the path that was given to the Supervisor. E.g., for a path of /node_app_root and a file /node_app_root/foo/index.js your module request should be for "foo/index.js" or "foo/index" or "foo".

Since the test suite requires npm dependencies before you can run the tests you will first need to run

cd test/js && npm install && cd ../..

After that you should be able to run

mix test

You can see examples of using promises in the tests here:

and from the JavaScript code here:

module.exports = async function echo(x, delay = 1000) {
  return new Promise((resolve) => setTimeout(() => resolve(x), delay))
}