Use ES6 and Webpacker in ActionCable guide.

[ci skip]

1 files changed, 160 insertions, 112 deletions

diff --git a/guides/source/action_cable_overview.md b/guides/source/action_cable_overview.md
index 2f602c3e0a..7809607574 100644
--- a/guides/source/action_cable_overview.md
+++ b/guides/source/action_cable_overview.md
@@ -147,16 +147,13 @@ established using the following JavaScript, which is generated by default by Rai
 #### Connect Consumer
 
 ```js
-// app/assets/javascripts/cable.js
-//= require action_cable
-//= require_self
-//= require_tree ./channels
+// app/javascript/channels/consumer.js
+// Action Cable provides the framework to deal with WebSockets in Rails.
+// You can generate new channels where WebSocket features live using the `rails generate channel` command.
 
-(function() {
-  this.App || (this.App = {});
+import ActionCable from "actioncable"
 
-  App.cable = ActionCable.createConsumer();
-}).call(this);
+export default ActionCable.createConsumer()
 ```
 
 This will ready a consumer that'll connect against `/cable` on your server by default.
@@ -167,12 +164,16 @@ you're interested in having.
 
 A consumer becomes a subscriber by creating a subscription to a given channel:
 
-```coffeescript
-# app/assets/javascripts/cable/subscriptions/chat.coffee
-App.cable.subscriptions.create { channel: "ChatChannel", room: "Best Room" }
+```js
+// app/javascript/cable/subscriptions/chat_channel.js
+import consumer from "./consumer"
+
+consumer.subscriptions.create({ channel: "ChatChannel", room: "Best Room" })
+
+// app/javascript/cable/subscriptions/appearance_channel.js
+import consumer from "./consumer"
 
-# app/assets/javascripts/cable/subscriptions/appearance.coffee
-App.cable.subscriptions.create { channel: "AppearanceChannel" }
+consumer.subscriptions.create({ channel: "AppearanceChannel" })
 ```
 
 While this creates the subscription, the functionality needed to respond to
@@ -181,9 +182,12 @@ received data will be described later on.
 A consumer can act as a subscriber to a given channel any number of times. For
 example, a consumer could subscribe to multiple chat rooms at the same time:
 
-```coffeescript
-App.cable.subscriptions.create { channel: "ChatChannel", room: "1st Room" }
-App.cable.subscriptions.create { channel: "ChatChannel", room: "2nd Room" }
+```js
+// app/javascript/cable/subscriptions/chat_channel.js
+import consumer from "./consumer"
+
+consumer.subscriptions.create({ channel: "ChatChannel", room: "1st Room" })
+consumer.subscriptions.create({ channel: "ChatChannel", room: "2nd Room" })
 ```
 
 ## Client-Server Interactions
@@ -256,24 +260,31 @@ When a consumer is subscribed to a channel, they act as a subscriber. This
 connection is called a subscription. Incoming messages are then routed to
 these channel subscriptions based on an identifier sent by the cable consumer.
 
-```coffeescript
-# app/assets/javascripts/cable/subscriptions/chat.coffee
-# Assumes you've already requested the right to send web notifications
-App.cable.subscriptions.create { channel: "ChatChannel", room: "Best Room" },
-  received: (data) ->
-    @appendLine(data)
-
-  appendLine: (data) ->
-    html = @createLine(data)
-    $("[data-chat-room='Best Room']").append(html)
-
-  createLine: (data) ->
-    """
-    <article class="chat-line">
-      <span class="speaker">#{data["sent_by"]}</span>
-      <span class="body">#{data["body"]}</span>
-    </article>
-    """
+```js
+// app/javascript/cable/subscriptions/chat_channel.js
+// Assumes you've already requested the right to send web notifications
+import consumer from "./consumer"
+
+consumer.subscriptions.create({ channel: "ChatChannel", room: "Best Room" }, {
+  received(data) {
+    this.appendLine(data)
+  },
+
+  appendLine(data) {
+    const html = this.createLine(data)
+    const element = document.querySelector("[data-chat-room='Best Room']")
+    element.insertAdjacentHTML("beforeend", html)
+  },
+
+  createLine(data) {
+    return `
+      <article class="chat-line">
+        <span class="speaker">${data["sent_by"]}</span>
+        <span class="body">${data["body"]}</span>
+      </article>
+    `
+  }
+})
 ```
 
 ### Passing Parameters to Channels
@@ -293,23 +304,30 @@ end
 An object passed as the first argument to `subscriptions.create` becomes the
 params hash in the cable channel. The keyword `channel` is required:
 
-```coffeescript
-# app/assets/javascripts/cable/subscriptions/chat.coffee
-App.cable.subscriptions.create { channel: "ChatChannel", room: "Best Room" },
-  received: (data) ->
-    @appendLine(data)
-
-  appendLine: (data) ->
-    html = @createLine(data)
-    $("[data-chat-room='Best Room']").append(html)
-
-  createLine: (data) ->
-    """
-    <article class="chat-line">
-      <span class="speaker">#{data["sent_by"]}</span>
-      <span class="body">#{data["body"]}</span>
-    </article>
-    """
+```js
+// app/javascript/cable/subscriptions/chat_channel.js
+import consumer from "./consumer"
+
+consumer.subscriptions.create({ channel: "ChatChannel", room: "Best Room" }, {
+  received(data) {
+    this.appendLine(data)
+  },
+
+  appendLine(data) {
+    const html = this.createLine(data)
+    const element = document.querySelector("[data-chat-room='Best Room']")
+    element.insertAdjacentHTML("beforeend", html)
+  },
+
+  createLine(data) {
+    return `
+      <article class="chat-line">
+        <span class="speaker">${data["sent_by"]}</span>
+        <span class="body">${data["body"]}</span>
+      </article>
+    `
+  }
+})
 ```
 
 ```ruby
@@ -340,13 +358,17 @@ class ChatChannel < ApplicationCable::Channel
 end
 ```
 
-```coffeescript
-# app/assets/javascripts/cable/subscriptions/chat.coffee
-App.chatChannel = App.cable.subscriptions.create { channel: "ChatChannel", room: "Best Room" },
-  received: (data) ->
-    # data => { sent_by: "Paul", body: "This is a cool chat app." }
+```js
+// app/javascript/cable/subscriptions/chat_channel.js
+import consumer from "./consumer"
+
+const chatChannel = consumer.subscriptions.create({ channel: "ChatChannel", room: "Best Room" }, {
+  received(data) {
+    // data => { sent_by: "Paul", body: "This is a cool chat app." }
+  }
+}
 
-App.chatChannel.send({ sent_by: "Paul", body: "This is a cool chat app." })
+chatChannel.send({ sent_by: "Paul", body: "This is a cool chat app." })
 ```
 
 The rebroadcast will be received by all connected clients, _including_ the
@@ -396,46 +418,69 @@ appear/disappear API could be backed by Redis, a database, or whatever else.
 
 Create the client-side appearance channel subscription:
 
-```coffeescript
-# app/assets/javascripts/cable/subscriptions/appearance.coffee
-App.cable.subscriptions.create "AppearanceChannel",
-  # Called when the subscription is ready for use on the server.
-  connected: ->
-    @install()
-    @appear()
-
-  # Called when the WebSocket connection is closed.
-  disconnected: ->
-    @uninstall()
-
-  # Called when the subscription is rejected by the server.
-  rejected: ->
-    @uninstall()
-
-  appear: ->
-    # Calls `AppearanceChannel#appear(data)` on the server.
-    @perform("appear", appearing_on: $("main").data("appearing-on"))
-
-  away: ->
-    # Calls `AppearanceChannel#away` on the server.
-    @perform("away")
-
-
-  buttonSelector = "[data-behavior~=appear_away]"
-
-  install: ->
-    $(document).on "turbolinks:load.appearance", =>
-      @appear()
-
-    $(document).on "click.appearance", buttonSelector, =>
-      @away()
-      false
-
-    $(buttonSelector).show()
-
-  uninstall: ->
-    $(document).off(".appearance")
-    $(buttonSelector).hide()
+```js
+// app/javascript/cable/subscriptions/appearance_channel.js
+import consumer from "./consumer"
+
+consumer.subscriptions.create("AppearanceChannel", {
+  // Called once when the subscription is created.
+  initialized() {
+    this.update = this.update.bind(this)
+  },
+
+  // Called when the subscription is ready for use on the server.
+  connected() {
+    this.install()
+    this.update()
+  },
+
+  // Called when the WebSocket connection is closed.
+  disconnected() {
+    this.uninstall()
+  },
+
+  // Called when the subscription is rejected by the server.
+  rejected() {
+    this.uninstall()
+  },
+
+  update() {
+    this.documentIsActive ? this.appear() : this.away()
+  },
+
+  appear() {
+    // Calls `AppearanceChannel#appear(data)` on the server.
+    this.perform("appear", { appearing_on: this.appearingOn })
+  },
+
+  away() {
+    // Calls `AppearanceChannel#away` on the server.
+    this.perform("away")
+  },
+
+  install() {
+    window.addEventListener("focus", this.update)
+    window.addEventListener("blur", this.update)
+    document.addEventListener("turbolinks:load", this.update)
+    document.addEventListener("visibilitychange", this.update)
+  },
+
+  uninstall() {
+    window.removeEventListener("focus", this.update)
+    window.removeEventListener("blur", this.update)
+    document.removeEventListener("turbolinks:load", this.update)
+    document.removeEventListener("visibilitychange", this.update)
+  },
+
+  get documentIsActive() {
+    return document.visibilityState == "visible" && document.hasFocus()
+  },
+
+  get appearingOn() {
+    const element = document.querySelector("[data-appearing-on]")
+    return element ? element.getAttribute("data-appearing-on") : null
+  }
+})
 ```
 
 ##### Client-Server Interaction
@@ -445,16 +490,16 @@ ActionCable.createConsumer("ws://cable.example.com")`. (`cable.js`). The
 **Server** identifies this connection by `current_user`.
 
 2. **Client** subscribes to the appearance channel via
-`App.cable.subscriptions.create(channel: "AppearanceChannel")`. (`appearance.coffee`)
+`consumer.subscriptions.create({ channel: "AppearanceChannel" })`. (`appearance_channel.js`)
 
 3. **Server** recognizes a new subscription has been initiated for the
 appearance channel and runs its `subscribed` callback, calling the `appear`
 method on `current_user`. (`appearance_channel.rb`)
 
 4. **Client** recognizes that a subscription has been established and calls
-`connected` (`appearance.coffee`) which in turn calls `@install` and `@appear`.
-`@appear` calls `AppearanceChannel#appear(data)` on the server, and supplies a
-data hash of `{ appearing_on: $("main").data("appearing-on") }`. This is
+`connected` (`appearance_channel.js`) which in turn calls `install` and `appear`.
+`appear` calls `AppearanceChannel#appear(data)` on the server, and supplies a
+data hash of `{ appearing_on: this.appearingOn }`. This is
 possible because the server-side channel instance automatically exposes all
 public methods declared on the class (minus the callbacks), so that these can be
 reached as remote procedure calls via a subscription's `perform` method.
@@ -488,13 +533,17 @@ end
 
 Create the client-side web notifications channel subscription:
 
-```coffeescript
-# app/assets/javascripts/cable/subscriptions/web_notifications.coffee
-# Client-side which assumes you've already requested
-# the right to send web notifications.
-App.cable.subscriptions.create "WebNotificationsChannel",
-  received: (data) ->
-    new Notification data["title"], body: data["body"]
+```js
+// app/javascript/cable/subscriptions/web_notifications_channel.js
+// Client-side which assumes you've already requested
+// the right to send web notifications.
+import consumer from "./consumer"
+
+consumer.subscriptions.create("WebNotificationsChannel", {
+  received(data) {
+    new Notification(data["title"], body: data["body"])
+  }
+})
 ```
 
 Broadcast content to a web notification channel instance from elsewhere in your
@@ -629,10 +678,9 @@ class Application < Rails::Application
 end
 ```
 
-You can use `App.cable = ActionCable.createConsumer()` to connect to the cable
-server if `action_cable_meta_tag` is invoked in the layout. A custom path is
-specified as first argument to `createConsumer` (e.g. `App.cable =
-ActionCable.createConsumer("/websocket")`).
+You can use `ActionCable.createConsumer()` to connect to the cable
+server if `action_cable_meta_tag` is invoked in the layout. Otherwise, A path is
+specified as first argument to `createConsumer` (e.g. `ActionCable.createConsumer("/websocket")`).
 
 For every instance of your server you create and for every worker your server
 spawns, you will also have a new instance of Action Cable, but the use of Redis