The JS module has functions and macros that help with interacting with JavaScript. These mostly correspond to JavaScript keywords that may be useful.

# Calling the JavaScript Debugger
JS.debugger()

# Getting the type of a value
JS.typeof(my_value)

# Creating a new JavaScript Map
map = JS.new(JS.Map, [])

In order to interact with JavaScript things in the global scope, append "JS" to them. The global scope corresponds to whatever the global object is in the JavaScript environment you are in. For example, in a browser this would be window or self:

# Calling alert
JS.alert("hello")

# Calling a method on Object
JS.Object.keys(my_object)

# Creating a new JavaScript Date
JS.new(JS.Date, [])

# Getting the outer width
JS.outerWidth

ElixirScript can use JavaScript modules from the supported modules systems. In order to do so, you must tell ElixirScript about them upfront.

If using ElixirScript in a mix project, you can do so inside of the ElixirScript configuration keyword list

  def project do
    [
      app: :my_project,
      elixir_script: [
        format: :es,
        js_modules: [
          {React, "react"},
          {ReactDOM, "react-dom"}
        ]
      ]
    ]
  end

Or if using the CLI, you can do so by passing each module via the js-module flag

elixirscript "app/elixirscript" -o dist --js-module React:react --js-module ReactDOM:react-dom

Interacting with these modules works the same as interacting with an ElixirScript module

React.createElement(...)

In order to start an ElixirScript application, you must first import it using whichever JavaScript module system you are using and then call Elixir.start

# Our ElixirScript module

defmodule Main do
  def start(:normal, args) do
    JS.console.log(args)
  end
end

//ES module example
import Elixir from './Elixir.App'
Elixir.start(Elixir.Main, [1, 2, 3])

In the above example, we have an ElixirScript module, Main with a start/2 function. This function is the entry point into your ElixirScript application. when we call Elixir.start, we give it this module's name (All modules when compiled begin with Elixir.) and a list of the initial args.

If you want to use an ElixirScript module inside of your JavaScript code, you can do so using Elixir.load.

# Our ElixirScript module

defmodule MyModule do
  def hi() do
    JS.alert("hello")
  end
end

const MyModule = Elixir.load(Elixir.MyModule);
MyModule.hi()