docs(attribute-directives): copy tweaks (#3284)

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Kapunahele Wong 2017-02-20 21:05:10 -05:00 committed by Ward Bell
parent 894ff63d36
commit dfd072f40e
2 changed files with 19 additions and 26 deletions

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@ -1,6 +1,8 @@
<!-- #docregion -->
<h1>My First Attribute Directive</h1>
<!-- #docregion applied -->
<p myHighlight>Highlight me!</p>
<!-- #enddocregion applied -->
<!-- #enddocregion -->
<!-- #docregion color-1 -->

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@ -24,13 +24,13 @@ a#directive-overview
## Directives overview
There are three kinds of directives in Angular:
1. Components &mdash; directives with a template.
1. Structural directives &mdash; change the DOM layout by adding and removing DOM elements.
1. Attribute directives &mdash; change the appearance or behavior of an element, component, or another directive.
1. Components&mdash;directives with a template.
1. Structural directives&mdash;change the DOM layout by adding and removing DOM elements.
1. Attribute directives&mdash;change the appearance or behavior of an element, component, or another directive.
*Components* are the most common of the three directives.
You saw a component for the first time in the [QuickStart](../quickstart.html) example.
You saw a component for the first time in the [QuickStart](../quickstart.html) guide.
*Structural Directives* change the structure of the view.
Two examples are [NgFor](template-syntax.html#ngFor) and [NgIf](template-syntax.html#ngIf).
@ -49,29 +49,19 @@ a#write-directive
the attribute.
The controller class implements the desired directive behavior.
This page demonstrates building a simple attribute
This page demonstrates building a simple _myHighlight_ attribute
directive to set an element's background color
when the user hovers over that element.
.l-sub-section
:marked
Technically, a directive isn't necessary to simply set the background color. Style binding can set styles as follows:
+makeExample('attribute-directives/ts/src/app/app.component.1.html','p-style-background')
:marked
Read more about [style binding](template-syntax.html#style-binding) on the [Template Syntax](template-syntax.html) page.
For a simple example, though, this will demonstrate how attribute directives work.
when the user hovers over that element. You can apply it like this:
+makeExample('attribute-directives/ts/src/app/app.component.1.html','applied')
:marked
### Write the directive code
Follow the [setup](setup.html) instructions for creating a new project
Follow the [setup](setup.html) instructions for creating a new local project
named <span ngio-ex>attribute-directives</span>.
:marked
Create the following source file in the indicated folder with the following code:
Create the following source file in `src/app` with the following code:
+makeExample('src/app/highlight.directive.1.ts')
block highlight-directive-1
@ -91,14 +81,14 @@ block highlight-directive-1
The [CSS selector for an attribute](https://developer.mozilla.org/en-US/docs/Web/CSS/Attribute_selectors)
is the attribute name in square brackets.
Here, the directive's selector is `[myHighlight]`.
Angular will locate all elements in the template that have an attribute named `myHighlight`.
Angular locates all elements in the template that have an attribute named `myHighlight`.
.l-sub-section
:marked
### Why not call it "highlight"?
Though *highlight* is a more concise name than *myHighlight* and would work,
a best practice is to prefix selector names to ensure
they don't conflict with standard HTML attributes.
This also reduces the risk colliding with third-party directive names.
This also reduces the risk of colliding with third-party directive names.
Make sure you do **not** prefix the `highlight` directive name with **`ng`** because
that prefix is reserved for Angular and using it could cause bugs that are difficult to diagnose. For a simple demo, the short prefix, `my`, helps distinguish your custom directive.
@ -120,7 +110,7 @@ a#apply-directive
## Apply the attribute directive
To use the new `HighlightDirective`, create a template that
applies the directive as an attribute to a paragraph (`<p>`) element.
In Angular terms, the `<p>` element will be the attribute **host**.
In Angular terms, the `<p>` element is the attribute **host**.
p
| Put the template in its own
code #[+adjExPath('app.component.html')]
@ -210,7 +200,7 @@ a#bindings
## Pass values into the directive with an _@Input_ data binding
Currently the highlight color is hard-coded _within_ the directive. That's inflexible.
Let the user of the directive set the color in the template with a binding.
In this section, you give the developer the power to set the highlight color while applying the directive.
Start by adding a `highlightColor` property to the directive class like this:
+makeExample('attribute-directives/ts/src/app/highlight.directive.2.ts','color', 'src/app/highlight.directive.ts')
@ -300,8 +290,9 @@ a#second-property
## Bind to a second property
This highlight directive has a single customizable property. In a real app, it may need more.
At the moment, the default color &mdash; the color that prevails until the user picks a highlight color &mdash;
is hard-coded as "red". Let the template developer set the default color.
At the moment, the default color&mdash;the color that prevails until
the user picks a highlight color&mdash;is hard-coded as "red".
Let the template developer set the default color.
Add a second **input** property to `HighlightDirective` called `defaultColor`:
+makeExcerpt('attribute-directives/ts/src/app/highlight.directive.ts', 'defaultColor','src/app/highlight.directive.ts (defaultColor)')