Add special API for JS, don't register implicitly after require

Fixes #2

README.adoc

@@ -74,7 +74,10 @@ asciidoctor -r {gem-name} -b html5s FILE...
 ----
 // Load asciidoctor.js and {gem-name}.
 const asciidoctor = require('asciidoctor.js')()
-require('{gem-name}')
+const asciidoctorHtml5s = require('{gem-name}')
+
+// Register the HTML5s converter and supporting extension.
+asciidoctorHtml5s.register()
 
 // Convert the content to HTML using html5s converter.
 const content = "Hello, *world!*!"

Rakefile

@@ -31,10 +31,13 @@ namespace :build do
       dynamic_require_severity: :error,
     })
     builder.append_paths 'lib'
-    builder.build 'asciidoctor-html5s'
+    builder.build 'asciidoctor/html5s'
 
     mkdir_p File.dirname(JS_FILE)
-    File.binwrite JS_FILE, builder.to_s
+    File.open(JS_FILE, 'w') do |file|
+      template = File.read('src/asciidoctor-html5s.tmpl.js')
+      file << template.sub('//OPAL-GENERATED-CODE//', builder.to_s)
+    end
     File.binwrite "#{JS_FILE}.map", builder.source_map
   end
 end

lib/asciidoctor/html5s.rb

@@ -1,8 +1,11 @@
-require 'asciidoctor/extensions' unless RUBY_PLATFORM == 'opal'
 require 'asciidoctor/html5s/version'
 require 'asciidoctor/html5s/converter'
 require 'asciidoctor/html5s/attached_colist_treeprocessor'
 
-Asciidoctor::Extensions.register do
-  treeprocessor Asciidoctor::Html5s::AttachedColistTreeprocessor
+unless RUBY_PLATFORM == 'opal'
+  require 'asciidoctor/extensions'
+
+  Asciidoctor::Extensions.register do
+    treeprocessor Asciidoctor::Html5s::AttachedColistTreeprocessor
+  end
 end

lib/asciidoctor/html5s/version.rb

@@ -1,5 +1,7 @@
+# frozen_string_literal: true
+
 module Asciidoctor
   module Html5s
-    VERSION = '0.1.0.beta.6'.freeze
+    VERSION = '0.1.0.beta.6'
   end
 end

src/asciidoctor-html5s.tmpl.js

@@ -0,0 +1,95 @@
+(function (Opal) {
+  function initialize (Opal) {
+//OPAL-GENERATED-CODE//
+  }
+
+  var mainModule
+
+  function resolveModule (name) {
+    if (!mainModule) {
+      checkAsciidoctor()
+      initialize(Opal)
+      mainModule = Opal.const_get_qualified(Opal.Asciidoctor, 'Html5s')
+    }
+    if (!name) {
+      return mainModule
+    }
+    return Opal.const_get_qualified(mainModule, name)
+  }
+
+  function checkAsciidoctor () {
+    if (typeof Opal.Asciidoctor === 'undefined') {
+      throw new TypeError('Asciidoctor.js is not loaded')
+    }
+  }
+
+  /**
+   * @return A new instance of `Asciidoctor::Html5s::AttachedColistTreeprocessor`.
+   */
+  function AttachedColistTreeprocessor () {
+    var processor =  resolveModule('AttachedColistTreeprocessor').$new()
+    processor.process = processor.$process
+
+    return processor
+  }
+
+  /**
+   * @param {string} backend The backend name.
+   * @param {Object} opts The converter options.
+   * @return A new instance of `Asciidoctor::Html5s::Converter`.
+   */
+  function Converter (backend, opts) {
+    var converter = resolveModule('Converter').$new(backend, Opal.hash(opts || {}))
+
+    converter.convert = function (node, transform, opts) {
+      return this.$convert(node, transform, Opal.hash(opts || {}))
+    }
+    return converter
+  }
+
+  /**
+   * @return {string} Version of this extension.
+   */
+  function getVersion () {
+    return resolveModule().$$const.VERSION.toString()
+  }
+
+  /**
+   * Registers the HTML5s converter and the supporting extension into Asciidoctor.
+   *
+   * @param registry The Asciidoctor extensions registry to register the
+   *   extension into. Defaults to the global Asciidoctor registry.
+   * @throws {TypeError} if the *registry* is invalid or Asciidoctor.js is not loaded.
+   */
+  function register (registry) {
+    if (!registry) {
+      checkAsciidoctor()
+      registry = Opal.Asciidoctor.Extensions
+    }
+    var processor = AttachedColistTreeprocessor()
+
+    // global registry
+    if (typeof registry.register === 'function') {
+      registry.register(function () {
+        this.treeProcessor(processor)
+      })
+    // custom registry
+    } else if (typeof registry.block === 'function') {
+      registry.treeProcessor(processor)
+    } else {
+      throw new TypeError('Invalid registry object')
+    }
+  }
+
+  var facade = {
+    AttachedColistTreeprocessor: AttachedColistTreeprocessor,
+    Converter: Converter,
+    getVersion: getVersion,
+    register: register,
+  }
+
+  if (typeof module !== 'undefined' && module.exports) {
+    module.exports = facade
+  }
+  return facade
+})(Opal);