docs(component-communication): copy edits and update TOCs (#3417)

public/docs/ts/latest/cookbook/component-communication.jade

@@ -13,21 +13,14 @@ include ../_util-fns
 
 <a id="toc"></a>
 :marked
-  ## Table of contents
+  # Contents
 
-  [Pass data from parent to child with input binding](#parent-to-child)
+  - [Pass data from parent to child with input binding](#parent-to-child)
+  - [Intercept input property changes with a setter](#parent-to-child-setter)
+  - [Intercept input property changes with `ngOnChanges()`](#parent-to-child-on-changes)
+  - [Parent calls an `@ViewChild()`](#parent-to-view-child)
+  - [Parent and children communicate via a service](#bidirectional-service)
 
-  [Intercept input property changes with a setter](#parent-to-child-setter)
-
-  [Intercept input property changes with *ngOnChanges*](#parent-to-child-on-changes)
-
-  [Parent listens for child event](#child-to-parent)
-  
-  [Parent interacts with child via a *local variable*](#parent-to-child-local-var)
-  
-  [Parent calls a *ViewChild*](#parent-to-view-child)
-
-  [Parent and children communicate via a service](#bidirectional-service)
 
 :marked
   **See the <live-example name="cb-component-communication"></live-example>**.
@@ -45,7 +38,7 @@ include ../_util-fns
   The second `@Input` aliases the child component property name `masterName` as `'master'`.
 
   The `HeroParentComponent` nests the child `HeroChildComponent` inside an `*ngFor` repeater,
-  binding its `master` string property to the child's `master` alias
+  binding its `master` string property to the child's `master` alias,
   and each iteration's `hero` instance to the child's `hero` property.
 
 +makeExample('cb-component-communication/ts/src/app/hero-parent.component.ts')
@@ -98,14 +91,14 @@ figure.image-display
 .l-main-section
 <a id="parent-to-child-on-changes"></a>
 :marked
-  ## Intercept input property changes with *ngOnChanges*
+  ## Intercept input property changes with *ngOnChanges()*
 
-  Detect and act upon changes to input property values with the `ngOnChanges` method of the `OnChanges` lifecycle hook interface.
+  Detect and act upon changes to input property values with the `ngOnChanges()` method of the `OnChanges` lifecycle hook interface.
 .l-sub-section
   :marked
-    May prefer this approach to the property setter when watching multiple, interacting input properties.
+    You may prefer this approach to the property setter when watching multiple, interacting input properties.
 
-    Learn about `ngOnChanges` in the [LifeCycle Hooks](../guide/lifecycle-hooks.html) chapter.
+    Learn about `ngOnChanges()` in the [LifeCycle Hooks](../guide/lifecycle-hooks.html) chapter.
 :marked
   This `VersionChildComponent` detects changes to the `major` and `minor` input properties and composes a log message reporting these changes:
 
@@ -148,15 +141,15 @@ figure.image-display
 +makeExample('cb-component-communication/ts/src/app/voter.component.ts')
 
 :marked
-  Clicking a button triggers emission of a `true` or `false` (the boolean *payload*).
+  Clicking a button triggers emission of a `true` or `false`, the boolean *payload*.
 
-  The parent `VoteTakerComponent` binds an event handler (`onVoted`) that responds to the child event
+  The parent `VoteTakerComponent` binds an event handler called `onVoted()` that responds to the child event
-  payload (`$event`) and updates a counter.
+  payload `$event` and updates a counter.
 
 +makeExample('cb-component-communication/ts/src/app/votetaker.component.ts')
 
 :marked
-  The framework passes the event argument &mdash; represented by `$event` &mdash; to the handler method, 
+  The framework passes the event argument&mdash;represented by `$event`&mdash;to the handler method,
   and the method processes it:
 
 figure.image-display
@@ -177,30 +170,30 @@ figure.image-display
   ## Parent interacts with child via *local variable*
 
   A parent component cannot use data binding to read child properties
-  or invoke child methods. We can do both 
+  or invoke child methods. You can do both
   by creating a template reference variable for the child element
   and then reference that variable *within the parent template*
   as seen in the following example.
 
   <a id="countdown-timer-example"></a>
-  We have a child `CountdownTimerComponent` that repeatedly counts down to zero and launches a rocket.
+  The following is a child `CountdownTimerComponent` that repeatedly counts down to zero and launches a rocket.
   It has `start` and `stop` methods that control the clock and it displays a
   countdown status message in its own template.
 +makeExample('cb-component-communication/ts/src/app/countdown-timer.component.ts')
 :marked
-  Let's see the `CountdownLocalVarParentComponent` that hosts the timer component.
+  The `CountdownLocalVarParentComponent` that hosts the timer component is as follows:
 
 +makeExample('cb-component-communication/ts/src/app/countdown-parent.component.ts', 'lv')
 :marked
   The parent component cannot data bind to the child's
   `start` and `stop` methods nor to its `seconds` property.
 
-  We can place a local variable (`#timer`) on the tag (`<countdown-timer>`) representing the child component.
+  You can place a local variable, `#timer`, on the tag `<countdown-timer>` representing the child component.
-  That gives us a reference to the child component itself and the ability to access
+  That gives you a reference to the child component and the ability to access
   *any of its properties or methods* from within the parent template.
 
-  In this example, we wire parent buttons to the child's `start` and `stop` and
+  This example wires parent buttons to the child's `start` and `stop` and
-  use interpolation to display the child's `seconds` property.
+  uses interpolation to display the child's `seconds` property.
 
   Here we see the parent and child working together.
 
@@ -223,52 +216,53 @@ a(id="countdown-tests")
 .l-main-section
 <a id="parent-to-view-child"></a>
 :marked
-  ## Parent calls a *ViewChild*
+  ## Parent calls an _@ViewChild()_
 
   The *local variable* approach is simple and easy. But it is limited because
   the parent-child wiring must be done entirely within the parent template.
   The parent component *itself* has no access to the child.
 
-  We can't use the *local variable* technique if an instance of the parent component *class*
+  You can't use the *local variable* technique if an instance of the parent component *class*
   must read or write child component values or must call child component methods.
 
   When the parent component *class* requires that kind of access,
-  we ***inject*** the child component into the parent as a *ViewChild*.
+  ***inject*** the child component into the parent as a *ViewChild*.
 
-  We'll illustrate this technique with the same [Countdown Timer](#countdown-timer-example) example. 
+  The following example illustrates this technique with the same 
-  We won't change its appearance or behavior. 
+  [Countdown Timer](#countdown-timer-example) example.
+  Neither its appearance nor its behavior will change.
   The child [CountdownTimerComponent](#countdown-timer-example) is the same as well.
 .l-sub-section
   :marked
-    We are switching from the *local variable* to the *ViewChild* technique
+    The switch from the *local variable* to the *ViewChild* technique
-    solely for the purpose of demonstration.
+    is solely for the purpose of demonstration.
 :marked
   Here is the parent, `CountdownViewChildParentComponent`:
 +makeExample('cb-component-communication/ts/src/app/countdown-parent.component.ts', 'vc')
 :marked
   It takes a bit more work to get the child view into the parent component *class*.
 
-  We import references to the `ViewChild` decorator and the `AfterViewInit` lifecycle hook.
+  First, you have to import references to the `ViewChild` decorator and the `AfterViewInit` lifecycle hook.
 
-  We inject the child `CountdownTimerComponent` into the private `timerComponent` property
+  Next, inject the child `CountdownTimerComponent` into the private `timerComponent` property
   via the `@ViewChild` property decoration.
 
   The `#timer` local variable is gone from the component metadata.
-  Instead we bind the buttons to the parent component's own `start` and `stop` methods and
+  Instead, bind the buttons to the parent component's own `start` and `stop` methods and
   present the ticking seconds in an interpolation around the parent component's `seconds` method.
 
   These methods access the injected timer component directly.
 
-  The `ngAfterViewInit` lifecycle hook is an important wrinkle.
+  The `ngAfterViewInit()` lifecycle hook is an important wrinkle.
   The timer component isn't available until *after* Angular displays the parent view.
-  So we display `0` seconds initially.
+  So it displays `0` seconds initially.
 
   Then Angular calls the `ngAfterViewInit` lifecycle hook at which time it is *too late*
   to update the parent view's display of the countdown seconds.
-  Angular's unidirectional data flow rule prevents us from updating the parent view's
+  Angular's unidirectional data flow rule prevents updating the parent view's
-  in the same cycle. We have to *wait one turn* before we can display the seconds.
+  in the same cycle. The app has to *wait one turn* before it can display the seconds.
 
-  We use `setTimeout` to wait one tick and then revise the `seconds` method so 
+  Use `setTimeout()` to wait one tick and then revise the `seconds()` method so
   that it takes future values from the timer component.
 
   ### Test it
@@ -304,12 +298,12 @@ a(id="countdown-tests")
 
 .l-sub-section
   :marked
-    Notice that we capture the `subscription` and unsubscribe when the `AstronautComponent` is destroyed.
+    Notice that this example captures the `subscription` and `unsubscribe()` when the `AstronautComponent` is destroyed.
     This is a memory-leak guard step. There is no actual risk in this app because the
     lifetime of a `AstronautComponent` is the same as the lifetime of the app itself.
     That *would not* always be true in a more complex application.
 
-    We do not add this guard to the `MissionControlComponent` because, as the parent,
+    You don't add this guard to the `MissionControlComponent` because, as the parent,
     it controls the lifetime of the `MissionService`.
 :marked
   The *History* log demonstrates that messages travel in both directions between
@@ -323,7 +317,7 @@ figure.image-display
   ### Test it
 
   Tests click buttons of both the parent `MissionControlComponent` and the `AstronautComponent` children
-  and verify that the *History* meets expectations:
+  and verify that the history meets expectations:
 
 +makeExample('cb-component-communication/e2e-spec.ts', 'bidirectional-service')