docs(template-syntax): get closer to a Dart version of template-syntax

Add doc regions to the TS version.
Update the Dart sample.
Publish a hidden draft of the Dart version.

Closes #758.
This commit is contained in:
Kathy Walrath 2016-01-26 15:48:03 -08:00
parent 0f5ea46590
commit 3d87360432
12 changed files with 856 additions and 169 deletions

2
.gitignore vendored
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@ -25,3 +25,5 @@ plnkr.html
*plnkr.no-link.html
public/docs/*/latest/guide/cheatsheet.json
protractor-results.txt
public/docs/ts/latest/guide/_.*.jade

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@ -0,0 +1,3 @@
linter:
rules:
- always_declare_return_types

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@ -1,15 +1,14 @@
// #docregion
library template_syntax.app_component;
import 'dart:html';
import 'dart:convert';
import 'dart:html';
import 'package:angular2/angular2.dart';
import 'package:template_syntax/hero.dart';
import 'package:template_syntax/hero_detail_component.dart';
import 'package:template_syntax/my_click_directive.dart';
enum _Color { Red, Green, Blue }
import 'hero.dart';
import 'hero_detail_component.dart';
import 'my_click_directive.dart';
enum Color { Red, Green, Blue }
@Component(
selector: 'my-app',
@ -24,37 +23,54 @@ class AppComponent {
String heroName;
String help;
String actionName = 'Go for it';
// String badCurly = 'special'; // XXX: This isn't working.
// String badCurly = 'bad, curly'; // XXX: This isn't working.
// String badCurly = 'bad curly'; // XXX: This isn't working.
String badCurly = 'bad'; // XXX: This isn't working.
// List<String> badCurly = ['bad', 'curly']; // XXX: This isn't working.
String title = 'Template Syntax';
String heroImageUrl = 'assets/images/hero.png';
String villainImageUrl = 'assets/images/villain.png';
String iconUrl = 'assets/images/ng-logo.png';
String chosenToe;
String toeChoice;
int val = 2;
bool canSave = true;
bool isActive = false;
bool isSpecial = true;
bool isUnchanged = true;
bool isSelected = false;
_Color color = _Color.Red;
Color color = Color.Red;
List<Hero> heroes = Hero.MockHeroes;
Hero selectedHero = Hero.MockHeroes[0];
Hero currentHero = Hero.MockHeroes[0];
Hero nullHero = null;
final Hero nullHero = null;
Map product = {'name': 'frimfram', 'price': 42};
Event clickity;
FormElement form;
String clickity = '';
String clickMessage = '';
String clickMessage2 = '';
final String iconUrl = 'assets/images/ng-logo.png';
// heroImageUrl = 'http://www.wpclipart.com/cartoon/people/hero/hero_silhoutte_T.png';
// Public Domain terms of use: http://www.wpclipart.com/terms.html
final String heroImageUrl = 'assets/images/hero.png';
// villainImageUrl = 'http://www.clker.com/cliparts/u/s/y/L/x/9/villain-man-hi.png'
// Public Domain terms of use http://www.clker.com/disclaimer.html
final String villainImageUrl = 'assets/images/villain.png';
// #docregion setClasses
Map classes = {
'saveable': false, // true
'modified': false, // false
'special': false // true
'saveable': false,
'modified': false,
'special': false
};
// #enddocregion setClasses
// #docregion setStyles
Map styles = {
'font-style': 'normal',
'font-weight': 'normal',
'font-size': 'smaller'
};
// #enddocregion setStyles
Map styles2 = {
'fontStyle': 'normal',
@ -66,31 +82,31 @@ class AppComponent {
void callFax(String value) => alerter('Faxing $value ...');
void callPhone(String value) => alerter('Calling $value ...');
void colorToggle() {
color = color == _Color.Red ? _Color.Blue : _Color.Red;
color = (color == Color.Red) ? Color.Blue : Color.Red;
}
int get getVal => val;
int getVal() => val;
void onCancel(MouseEvent event) {
DivElement el = event.target;
var evtMsg = event != null ? 'Event target is ${el.innerHtml}' : '';
var evtMsg = event != null ? 'Event target is ${el.innerHtml}.' : '';
alerter('Canceled. $evtMsg');
}
void onClickMe(MouseEvent event) {
DivElement el = event.target;
var evtMsg = event != null ? 'Event target class is ${el.className}' : '';
var evtMsg = event != null ? 'Event target class is ${el.className}.' : '';
alerter('Click me. $evtMsg');
}
bool onSave([MouseEvent event = null]) {
var evtMsg =
event != null ? ' Event target is ${event.target.innerHtml}' : '';
alerter('Saved.$evtMsg');
event != null ? ' Event target is ${event.target.innerHtml}.' : '';
alerter('Saved. $evtMsg');
return false;
}
void onHeroDeleted(Hero hero) => alerter('Deleted hero: ${hero.firstName}');
void onHeroDeleted([Hero hero]) => alerter('Deleted hero: ${hero?.firstName}');
void onSubmit(NgForm form) {
var evtMsg = form.valid
@ -108,40 +124,32 @@ class AppComponent {
return JSON.encode(showStyles);
}
// #docregion setStyles
Map setStyles() {
styles['font-style'] = canSave ? 'italic' : 'normal';
styles['font-weight'] = !isUnchanged ? 'bold' : 'normal';
styles['font-size'] = isSpecial ? 'x-large' : 'smaller';
return styles;
}
// #enddocregion setStyles
// #docregion setStyles2
Map setStyles2() {
// camelCase style properties work too [PENDING: no, they don't]
styles2['fontStyle'] = canSave ? 'italic' : 'normal';
styles2['fontWeight'] = !isUnchanged ? 'bold' : 'normal';
styles2['fontSize'] = isSpecial ? 'x-large' : 'smaller';
return styles2;
}
// #enddocregion setStyles2
// #docregion setClasses
Map setClasses() {
classes['saveable'] = canSave;
classes['modified'] = !isUnchanged;
classes['special'] = isSpecial;
classes['saveable'] = canSave; // true
classes['modified'] = !isUnchanged; // false
classes['special'] = isSpecial; // true
return classes;
}
// #enddocregion setClasses
// #docregion setStyles
Map setStyles() {
styles['font-style'] = canSave ? 'italic' : 'normal'; // italic
styles['font-weight'] = !isUnchanged ? 'bold' : 'normal'; // normal
styles['font-size'] = isSpecial ? '24px' : '8px'; // 24px
return styles;
}
// #enddocregion setStyles
String toeChooser(Element picker) {
List<Element> choices = picker.children;
for (var i = 0; i < choices.length; i++) {
var choice = choices[i];
if (choice.checked) {
chosenToe = choice.value;
return chosenToe;
toeChoice = choice.value;
return toeChoice;
}
}
}

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@ -23,7 +23,7 @@
<!-- #docregion sum-2 -->
<!-- "The sum of 1 + 1 is not 4" -->
<p>The sum of 1 + 1 is not {{1 + 1 + getVal}}</p>
<p>The sum of 1 + 1 is not {{1 + 1 + getVal()}}</p>
<!-- #enddocregion sum-2 -->
@ -69,9 +69,9 @@
<!-- #docregion event-binding-syntax-1 -->
<button (click) = "onSave()">Save</button>
<hero-detail (deleted)="onHeroDeleted()"></hero-detail>
<div myClick (myClick)="clicked=$event">click me</div>
<div myClick (myClick)="clickity=$event">click me</div>
<!-- #enddocregion event-binding-syntax-1 -->
<!-- {{clicked}} --> <!-- causes exception in Dart version -->
{{clickity}}
<br><br>
<div>
@ -146,15 +146,17 @@ button</button>
<!-- #docregion property-binding-6 -->
<!-- Doesn't work! HeroDetailComponent expects a Hero, not a string -->
<!--<hero-detail hero="…what do we do here??? …"></hero-detail>--> <!--THROWS ERROR IN DART-->
<!-- <hero-detail hero="…what do we do here??? …"></hero-detail> -->
<!-- #enddocregion property-binding-6 -->
<!-- In checked mode, uncommenting the hero-detail above causes this:
EXCEPTION: type 'String' is not a subtype of type 'Hero' of 'value'. -->
<!-- #docregion property-binding-vs-interpolation -->
<img src="{{heroImageUrl}}">
<img [src]="'' + heroImageUrl">
<img [src]="heroImageUrl">
<div>The title is {{title}}</div>
<div [textContent]="'The title is '+title"></div>
<div [textContent]="'The title is ' + title"></div>
<!-- #enddocregion property-binding-vs-interpolation -->
<!-- attribute binding -->
@ -208,9 +210,10 @@ button</button>
<!-- #enddocregion class-binding-1 -->
<!-- #docregion class-binding-2 -->
<!-- reset all class names with a string binding -->
<!-- reset/override all class names with a binding -->
<div class="bad curly special"
[class]="'bad curly'">Bad curly</div>
[class]="badCurly">Bad curly</div> <!-- Doesn't work, due to
github.com/angular/angular/issues/6901 -->
<!-- #enddocregion class-binding-2 -->
<!-- #docregion class-binding-3 -->
@ -257,10 +260,10 @@ button</button>
<!-- `myClick` is an event on the custom `MyClickDirective` -->
<!-- #docregion my-click -->
<div myClick (myClick)="clickity=$event">click with myClick</div>
<div myClick (myClick)="clickMessage=$event">click with myClick</div>
<!-- #enddocregion my-click -->
<!-- #enddocregion event-binding-3 -->
{{clickity}}
{{clickMessage}}
</div>
@ -362,32 +365,22 @@ bindon-ngModel
<!-- #docregion NgStyle-1 -->
<div [style.font-size]="isSpecial ? 'x-large' : 'smaller'" >
This div is x-large
This div is x-large.
</div>
<!-- #enddocregion NgStyle-1 -->
<h3>Use setStyles() - CSS property names</h3>
<p>setStyles returns {{setStyles() | json}}</p>
<p>setStyles returns {{setStyles()}}.</p>
<!-- #docregion NgStyle-2 -->
<div [ngStyle]="setStyles()">
This div is italic, normal weight, and x-large
This div is italic, normal weight, and extra large (24px).
</div>
<!-- #enddocregion NgStyle-2 -->
<div [ngStyle]="setStyles()" #styleDiv>
After setStyles(), the styles are "{{getStyles(styleDiv)}}"
</div>
<h3>Use setStyles2() - camelCase style property names</h3>
<p>setStyles2 returns {{setStyles2() | json}}</p>
<!-- #docregion NgStyle-3 -->
<div [ngStyle]="setStyles2()">
This div is italic, normal weight, and x-large
</div>
<!-- #enddocregion NgStyle-3 -->
<div [ngStyle]="setStyles2()" #styleDiv2>
After setStyles2(), the styles are "{{getStyles(styleDiv2)}}"
</div>
<p>After setStyles(), the DOM confirms that the styles are
<span [ngStyle]="setStyles()" #styleDiv>
{{getStyles(styleDiv)}}
</span>.
</p>
<!-- not used in chapter -->
@ -401,7 +394,7 @@ bindon-ngModel
<!-- #enddocregion NgIf-1 -->
<!-- #docregion NgIf-2 -->
<!-- not displayed because nullHero is falsey.
<!-- not displayed because nullHero is false.
`nullHero.firstName` never has a chance to fail -->
<div *ngIf="nullHero != null">Hello, {{nullHero.firstName}}</div>
@ -446,17 +439,17 @@ bindon-ngModel
</fieldset>
<div class="toe">
<div *ngIf="chosenToe == null">Pick a toe</div>
<div *ngIf="chosenToe != null">You picked
<!-- #docregion NgSwitch -->
<span [ngSwitch]="chosenToe">
<template [ngSwitchWhen]="'Eenie'">Eenie</template>
<template [ngSwitchWhen]="'Meanie'">Meanie</template>
<template [ngSwitchWhen]="'Miney'">Miney</template>
<template [ngSwitchWhen]="'Moe'">Moe</template>
<template ngSwitchDefault>Other</template>
</span>
<!-- #enddocregion NgSwitch -->
<div *ngIf="toeChoice == null">Pick a toe</div>
<div *ngIf="toeChoice != null">You picked
<!-- #docregion NgSwitch -->
<span [ngSwitch]="toeChoice">
<template [ngSwitchWhen]="'Eenie'">Eenie</template>
<template [ngSwitchWhen]="'Meanie'">Meanie</template>
<template [ngSwitchWhen]="'Miney'">Miney</template>
<template [ngSwitchWhen]="'Moe'">Moe</template>
<template ngSwitchDefault>Other</template>
</span>
<!-- #enddocregion NgSwitch -->
</div>
</div>
@ -480,8 +473,8 @@ bindon-ngModel
<br>
<div class="box">
<!-- #docregion NgFor-3 -->
<!-- Ex: 1 - Hercules Son of Zeus -->
<!-- #docregion NgFor-3 -->
<div *ngFor="#hero of heroes, #i=index">{{i + 1}} - {{hero.fullName}}</div>
<!-- #enddocregion NgFor-3 -->
</div>
@ -567,10 +560,8 @@ bindon-ngModel
</hero-detail>
<!-- #enddocregion io-2 -->
<!-- <div myClick2 (myClick)="clicked2=$event">myClick2</div>
{{clicked2}}
PENDING: I don't see clicked2 defined anywhere in the TS example
-->
<div myClick2 (myClick)="clickMessage2=$event">myClick2</div>
{{clickMessage2}}
<!-- Pipes -->
<hr><h2>Pipes</h2>
@ -591,14 +582,10 @@ PENDING: I don't see clicked2 defined anywhere in the TS example
<!-- #enddocregion pipes-3 -->
<!-- #docregion pipes-json -->
<!--<div>{{currentHero | json}}</div>--> <!-- PENDING: uncomment? -->
<!-- Don't suggest using json for debugging; you'd probably use toString() instead.
Is there a good use for the json pipe in Dart? -->
<!--<div>{{currentHero | json}}</div>-->
<!-- Output:
{ "firstName": "Hercules", "lastName": "Son of Zeus",
"birthdate": "1970-02-25T08:00:00.000Z",
"url": "http://www.imdb.com/title/tt0065832/",
"rate": 325, "id": 1 }
-->
<!-- #enddocregion pipes-json -->
@ -606,7 +593,7 @@ PENDING: I don't see clicked2 defined anywhere in the TS example
<div>
<!-- pipe price to USD and display the $ symbol -->
<!--<label>Price: </label>{{product.price | currency:'USD':true}}--> <!-- PENDING: uncomment? -->
<label>Price: </label>{{product['price'] | currency:'$'}}
</div>
@ -632,11 +619,12 @@ PENDING: I don't see clicked2 defined anywhere in the TS example
</div>
<!--
The null hero's name is {{nullHero.firstName}}
See console log
TypeError: Cannot read property 'firstName' of null in [null]
See console log:
EXCEPTION: The null object does not have a getter 'firstName'.
-->
<!-- #docregion elvis-4 -->
@ -644,11 +632,7 @@ See console log
<div *ngIf="nullHero != null">The null hero's name is {{nullHero.firstName}}</div>
<!-- #enddocregion elvis-4 -->
<div>
<!-- #docregion elvis-5 -->
The null hero's name is {{nullHero != null && nullHero.firstName != null}} <!-- PENDING: ??? -->
<!-- #enddocregion elvis-5 -->
</div>
<!-- skip docregion elvis-5 -->
<div>
<!-- #docregion elvis-6 -->
@ -660,8 +644,9 @@ See console log
<!-- Todo: discuss this in the Style binding section -->
<!-- enums in bindings -->
<!--
<hr><h2>Enums in binding</h2>
<p>The name of the Color.Red enum is {{color}}</p> <!-- PENDING: Color[Color.Red]?? -->
<p>The current color number is {{color}}</p>
<p><button [style.color]="color" (click)="colorToggle()">Enum Toggle</button> <!-- PENDING: color -> Color[color]? -->
<p><button [style.color]="color.toString()" (click)="colorToggle()">Enum Toggle</button>
-->

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@ -1,6 +1,4 @@
// #docregion
library template_syntax.hero;
class Hero {
static int _nextId = 1;
@ -18,7 +16,7 @@ class Hero {
static List<Hero> MockHeroes = [
new Hero('Hercules',
lastName: 'Son of Zeus',
birthdate: new DateTime(1970, 1, 25),
birthdate: new DateTime(1970, 2, 25),
url: 'http://www.imdb.com/title/tt0065832/',
rate: 325),
new Hero('eenie', lastName: 'toe'),
@ -27,5 +25,10 @@ class Hero {
new Hero('Moe', lastName: 'Toe')
];
String get fullName => '$firstName $lastName';
String get fullName {
if (lastName == null) return firstName;
return '$firstName $lastName';
}
String toString() => '$fullName (rate: $rate)';
}

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@ -1,8 +1,8 @@
// #docplaster
// #docregion
library template_syntax.hero_detail_component;
import 'package:angular2/angular2.dart';
import 'package:template_syntax/hero.dart';
import 'hero.dart';
var nextHeroDetailId = 1;
@ -11,28 +11,40 @@ var nextHeroDetailId = 1;
// #enddocregion input-output-2
selector: 'hero-detail',
// #docregion input-output-2
// ...
inputs: const ['hero'],
outputs: const ['deleted'],
// #enddocregion input-output-2
template: '''<div id="lh{{hero?.id}}">
{{hero?.fullName}}
template: '''
<div>
<span [style.text-decoration]="lineThrough" >{{hero?.fullName}}</span>
<img src="{{heroImageUrl}}" style="height:24px">
<a href="#lh{{hero?.id}}" (click)="onDelete()">delete</a>
</div>'''
<a (click)="onDelete()">delete</a>
</div>
'''
// #docregion input-output-2
)
// #enddocregion input-output-2
class HeroDetailComponent {
Hero hero;
// #docregion deleted
Hero hero = new Hero('Zzzzzzzz'); // default sleeping hero
String heroImageUrl = 'assets/images/hero.png';
final EventEmitter deleted = new EventEmitter<Hero>();
String lineThrough = ''; // PENDING: use null instead?
onDelete() {
deleted.add(hero);
// #docregion deleted
final EventEmitter deleted = new EventEmitter<Hero>();
// #enddocregion deleted
HeroDetailComponent() {
deleted.listen((Hero _) {
lineThrough = (lineThrough == '') ? 'line-through' : '';
});
}
// #enddocregion deleted
// #docregion deleted
onDelete() {
deleted.emit(hero);
}
// #enddocregion deleted
}
@Component(
@ -41,7 +53,8 @@ class HeroDetailComponent {
inputs: ['hero'],
outputs: ['deleted'],
*/
template: '''<div style="border: 1px solid black; padding:3px">
template: '''
<div style="border: 1px solid black; padding:3px">
<img src="{{heroImageUrl}}" style="float:left; margin-right:8px;">
<div><b>{{hero?.fullName}}</b></div>
<div>First: {{hero?.firstName}}</div>
@ -51,17 +64,17 @@ class HeroDetailComponent {
<div>Rate/hr: {{hero?.rate | currency:'EUR'}}</div>
<br clear="all">
<button (click)="onDelete()">Delete</button>
</div>''')
</div>
''')
class BigHeroDetailComponent extends HeroDetailComponent {
// #docregion input-output-1
@Input() Hero hero;
@Output()
final EventEmitter deleted = new EventEmitter<Hero>();
@Output() final EventEmitter deleted = new EventEmitter<Hero>();
// #enddocregion input-output-1
String heroImageUrl = 'assets/images/hero.png';
onDelete() {
deleted.add(hero);
deleted.emit(hero);
}
}

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@ -1,6 +1,4 @@
// #docregion
library template_syntax.my_click_directive;
// #docplaster
import 'dart:html';
import 'package:angular2/angular2.dart';
@ -8,12 +6,18 @@ import 'package:angular2/angular2.dart';
@Directive(selector: '[myClick]')
class MyClickDirective {
// #docregion my-click-output-1
@Output()
final EventEmitter clicks = new EventEmitter<String>();
// @Output(alias) [type info] propertyName = ...
@Output('myClick') final EventEmitter clicks = new EventEmitter<String>();
// #enddocregion my-click-output-1
bool _toggle = false;
MyClickDirective(ElementRef el) {
el.nativeElement.onClick.listen(this.clicks.add('Click!'));
Element nativeEl = el.nativeElement;
nativeEl.onClick.listen((Event e) {
_toggle = !_toggle;
clicks.emit(_toggle ? 'Click!' : '');
});
}
}
@ -22,12 +26,17 @@ class MyClickDirective {
// #enddocregion my-click-output-2
selector: '[myClick2]',
// #docregion my-click-output-2
outputs: const ['clicks:myClick'])
// ...
outputs: const ['clicks:myClick']) // propertyName:alias
// #enddocregion my-click-output-2
class MyClickDirective2 {
final EventEmitter clicks = new EventEmitter<String>();
bool _toggle = false;
MyClickDirective(ElementRef el) {
el.nativeElement.onClick.listen(this.clicks.add('Click!'));
MyClickDirective2(ElementRef el) {
el.nativeElement.onClick.listen((Event e) {
_toggle = !_toggle;
clicks.emit(_toggle ? 'Click2!' : '');
});
}
}

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@ -1,12 +1,19 @@
# #docregion
name: template_syntax
description: Template Syntax
version: 0.0.1
environment:
sdk: '>=1.13.0 <2.0.0'
dependencies:
angular2: 2.0.0-beta.0
angular2: 2.0.0-beta.3
browser: ^0.10.0
dart_to_js_script_rewriter: ^0.1.0
transformers:
- angular2:
platform_pipes: 'package:angular2/common.dart#COMMON_PIPES'
platform_directives:
- 'package:angular2/common.dart#COMMON_DIRECTIVES'
- 'package:angular2/common.dart#FORM_DIRECTIVES'
entry_points: web/main.dart
- dart_to_js_script_rewriter

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@ -3,11 +3,11 @@
<html>
<head>
<title>Template Syntax</title>
<link rel="stylesheet" href="style.css">
<link rel="stylesheet" href="styles.css">
<script defer src="main.dart" type="application/dart"></script>
<script defer src="packages/browser/dart.js"></script>
</head>
<body>
<my-app>Loading...</my-app>
</body>
</html>
</html>

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@ -0,0 +1,397 @@
include ../../../../_includes/_util-fns
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'intro')
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'html-1')
+makeExample('template-syntax/dart/lib/app_component.html', 'my-first-app')(format=".")
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'html-2')
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'interpolation-1')
+makeExample('template-syntax/dart/lib/app_component.html', 'first-interpolation')(format=".")
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'interpolation-2')
+makeExample('template-syntax/dart/lib/app_component.html', 'title+image')(format=".")
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'interpolation-3')
+makeExample('template-syntax/dart/lib/app_component.html', 'sum-1')(format=".")
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'interpolation-4')
+makeExample('template-syntax/dart/lib/app_component.html', 'sum-2')(format=".")
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'interpolation-5')
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'template-expressions-1')
:marked
We write template expressions in a language that looks like Dart.
Many Dart expressions are legal template expressions, but not all.
Dart expressions that have or promote side effects are prohibited,
including: **[QUESTION: is this list correct? I removed mentions of chaining with , and ;.]**
* assignments (`=`, `+=`, `-=`, ...)
* creating instances using `new` or `const`
* increment and decrement (`++` and `--`)
Other notable differences from Dart syntax include:
**[QUESTION: I wasn't able to use Dart interpolation inside a String,
which I had just assumed would work. How should we talk about that?
What else isn't allowed?]**
* no support for the bitwise operators `|` and `&`
* new [template expression operators](#expression-operators), such as `|`
.callout.is-helpful
header Dart difference: Template expression operators
:marked
[PENDING: say something about stuff you might find in a24ts template expressions
but not in dart template expressions, and vice versa.]
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'template-expressions-context')
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'template-expressions-guidelines')
:marked
Dependent values should not change during a single turn of the event loop.
If an idempotent expression returns a string or a number, it returns the same string or number
when called twice in a row. If the expression returns an object (including a `DateTime`, `Map`, or `List`),
it returns the same object *reference* when called twice in a row.
.callout.is-helpful
header Dart difference: Arrays are lists
:marked
Arrays in JavaScript correspond to lists in Dart
(instances of the `List` class).
This chapter uses _array_ and _list_ interchangeably.
For more information, see
[Lists](https://www.dartlang.org/docs/dart-up-and-running/ch02.html#lists)
in the [Dart language tour](https://www.dartlang.org/docs/dart-up-and-running/ch02.html).
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'template-statements-1')
:marked
Like template expressions, template *statements* use a language that looks like Dart.
The template statement parser is different than the template expression parser and
specifically supports both basic assignment (`=`) and chaining expressions with semicolons (`;`) and commas (`,`).
**[QUESTION: is that true — would `,` really work? is "chaining" really the word we want to use?]**
However, certain Dart syntax is not allowed:
* the `new` and `const` keywords **[QUESTION: I guessed about `const`. Is it true?]**
* increment and decrement operators, `++` and `--`
* operator assignment, such as `+=` and `-=`
* the bitwise operators `|` and `&`
* the [template expression operators](#expression-operators)
**[QUESTION: can you really not use `?.`?]**
.callout.is-helpful
header Dart difference: Template statement operators
:marked
[PENDING: say something about stuff you might find in a24ts statements
but not in dart statements, and vice versa.]
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'template-statements-3')
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'binding-syntax-1')
+makeExample('template-syntax/dart/lib/app_component.html', 'img+button')(format=".")
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'binding-syntax-2')
+makeExample('template-syntax/dart/lib/app_component.html', 'hero-detail-1')(format=".")
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'binding-syntax-3')
+makeExample('template-syntax/dart/lib/app_component.html', 'disabled-button-1')(format=".")
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'binding-syntax-4')
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'binding-syntax-attribute-vs-property')
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'binding-syntax-5')
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'binding-syntax-world-without-attributes')
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'binding-syntax-targets')
<div width="90%">
table
tr
th Binding type
th Target
th Examples
tr
td Property
td.
Element&nbsp;property<br>
Component&nbsp;property<br>
Directive&nbsp;property
td
+makeExample('template-syntax/dart/lib/app_component.html', 'property-binding-syntax-1')(format=".")
tr
td Event
td.
Element&nbsp;event<br>
Component&nbsp;event<br>
Directive&nbsp;event
td
+makeExample('template-syntax/dart/lib/app_component.html', 'event-binding-syntax-1')(format=".")
tr
td Two-way
td.
Event and property
td
+makeExample('template-syntax/dart/lib/app_component.html', '2-way-binding-syntax-1')(format=".")
tr
td Attribute
td.
Attribute
(the&nbsp;exception)
td
+makeExample('template-syntax/dart/lib/app_component.html', 'attribute-binding-syntax-1')(format=".")
tr
td Class
td.
<code>class</code> property
td
+makeExample('template-syntax/dart/lib/app_component.html', 'class-binding-syntax-1')(format=".")
tr
td Style
td.
<code>style</code> property
td
+makeExample('template-syntax/dart/lib/app_component.html', 'style-binding-syntax-1')(format=".")
</div>
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'binding-syntax-end')
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'property-binding-1')
+makeExample('template-syntax/dart/lib/app_component.html', 'property-binding-1')(format=".")
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'property-binding-2')
+makeExample('template-syntax/dart/lib/app_component.html', 'property-binding-2')(format=".")
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'property-binding-3')
+makeExample('template-syntax/dart/lib/app_component.html', 'property-binding-3')(format=".")
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'property-binding-4')
+makeExample('template-syntax/dart/lib/app_component.html', 'property-binding-4')(format=".")
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'property-binding-5')
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'property-binding-6')
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'property-binding-7')
+makeExample('template-syntax/dart/lib/app_component.html', 'property-binding-1')(format=".")
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'property-binding-8')
+makeExample('template-syntax/dart/lib/app_component.html', 'property-binding-5')(format=".")
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'property-binding-9')
+makeExample('template-syntax/dart/lib/app_component.html', 'property-binding-3')(format=".")
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'property-binding-10')
+makeExample('template-syntax/dart/lib/app_component.html', 'property-binding-4')(format=".")
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'property-binding-11')
+makeExample('template-syntax/dart/lib/app_component.html', 'property-binding-6')(format=".")
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'property-binding-12')
+makeExample('template-syntax/dart/lib/app_component.html', 'property-binding-vs-interpolation')(format=".")
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'property-binding-13')
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'other-bindings-1')
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'other-bindings-2')
+makeExample('template-syntax/dart/lib/app_component.html', 'attrib-binding-colspan')(format=".")
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'other-bindings-3')
+makeExample('template-syntax/dart/lib/app_component.html', 'attrib-binding-aria')(format=".")
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'other-bindings-class-1')
+makeExample('template-syntax/dart/lib/app_component.html', 'class-binding-1')(format=".")
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'other-bindings-class-2')
+makeExample('template-syntax/dart/lib/app_component.html', 'class-binding-2')(format=".")
//
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'other-bindings-class-3')
:marked
Finally, we can bind to a specific class name.
Angular adds the class when the template expression evaluates to `true`.
It removes the class when the expression evaluates to `false`.
+makeExample('template-syntax/dart/lib/app_component.html', 'class-binding-3')(format=".")
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'other-bindings-class-4')
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'other-bindings-style-1')
+makeExample('template-syntax/dart/lib/app_component.html', 'style-binding-1')(format=".")
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'other-bindings-style-2')
+makeExample('template-syntax/dart/lib/app_component.html', 'style-binding-2')(format=".")
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'other-bindings-style-3')
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'event-binding-1')
+makeExample('template-syntax/dart/lib/app_component.html', 'event-binding-1')(format=".")
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'event-binding-2')
+makeExample('template-syntax/dart/lib/app_component.html', 'event-binding-1')(format=".")
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'event-binding-3')
+makeExample('template-syntax/dart/lib/app_component.html', 'event-binding-2')(format=".")
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'event-binding-4')
+makeExample('template-syntax/dart/lib/app_component.html', 'event-binding-3')(format=".")
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'event-binding-5')
+makeExample('template-syntax/dart/lib/app_component.html', 'without-NgModel')(format=".")
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'event-binding-6')
+makeExample('template-syntax/dart/lib/hero_detail_component.dart', 'deleted', 'lib/hero_detail_component.dart (excerpt)')(format=".")
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'event-binding-7')
+makeExample('template-syntax/dart/lib/app_component.html', 'event-binding-to-component')(format=".")
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'event-binding-8')
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'ngModel-1')
+makeExample('template-syntax/dart/lib/app_component.html', 'NgModel-1')(format=".")
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'ngModel-2')
+makeExample('template-syntax/dart/lib/app_component.html', 'NgModel-2')(format=".")
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'ngModel-3')
+makeExample('template-syntax/dart/lib/app_component.html', 'without-NgModel')(format=".")
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'ngModel-4')
+makeExample('template-syntax/dart/lib/app_component.html', 'NgModel-3')(format=".")
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'ngModel-5')
+makeExample('template-syntax/dart/lib/app_component.html', 'NgModel-1')(format=".")
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'ngModel-6')
+makeExample('template-syntax/dart/lib/app_component.html', 'NgModel-4')(format=".")
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'ngModel-7')
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'directives-1')
+makeExample('template-syntax/dart/lib/app_component.html', 'event-binding-1')(format=".")
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'directives-2')
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'directives-ngClass-1')
+makeExample('template-syntax/dart/lib/app_component.html', 'class-binding-3a')(format=".")
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'directives-ngClass-2')
+makeExample('template-syntax/dart/lib/app_component.dart', 'setClasses')(format=".")
// PENDING: Add "Dart difference" for returning maps in Dart? for omitting unnecessary `this.`s?
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'directives-ngClass-3')
+makeExample('template-syntax/dart/lib/app_component.html', 'NgClass-1')(format=".")
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'directives-ngStyle-1')
+makeExample('template-syntax/dart/lib/app_component.html', 'NgStyle-1')(format=".")
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'directives-ngStyle-2')
+makeExample('template-syntax/dart/lib/app_component.dart', 'setStyles')(format=".")
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'directives-ngStyle-3')
+makeExample('template-syntax/dart/lib/app_component.html', 'NgStyle-2')(format=".")
//
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'directives-ngIf-1')
<a id="ngIf"></a>
.l-main-section
:marked
### NgIf
We can add an element subtree (an element and its children) to the DOM by binding an `NgIf` directive to a `true` expression.
+makeExample('template-syntax/dart/lib/app_component.html', 'NgIf-1')(format=".")
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'directives-ngIf-2')
//
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'directives-ngIf-3')
:marked
Binding to a false expression removes the element subtree from the DOM.
+makeExample('template-syntax/dart/lib/app_component.html', 'NgIf-2')(format=".")
.callout.is-helpful
header Dart difference: No truthy values
:marked
In checked mode, Dart expects Boolean values
(those with type `bool`) to be either `true` or `false`.
Even in production mode, the only value Dart treats as `true` is
the value `true`; all other values are `false`.
TypeScript and JavaScript, on the other hand, treat
many values (including non-null objects) as true.
A TypeScript Angular 2 program, for example, often has code like
`*ngIf="currentHero"` where a Dart program has code like
`*ngIf="currentHero != null"`.
When converting TypeScript code to Dart code, watch out for
true/false problems. For example, forgetting the `!= null`
can lead to error messages such as
"[TODO: Put error message here]".
For more information, see
[Booleans](https://www.dartlang.org/docs/dart-up-and-running/ch02.html#booleans)
in the [Dart language tour](https://www.dartlang.org/docs/dart-up-and-running/ch02.html).
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'directives-ngIf-4')
+makeExample('template-syntax/dart/lib/app_component.html', 'NgIf-3')(format=".")
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'directives-ngIf-5')
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'directives-ngSwitch-1')
+makeExample('template-syntax/dart/lib/app_component.html', 'NgSwitch')(format=".")
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'directives-ngSwitch-2')
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'directives-ngFor-1')
+makeExample('template-syntax/dart/lib/app_component.html', 'NgFor-1')(format=".")
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'directives-ngFor-2')
+makeExample('template-syntax/dart/lib/app_component.html', 'NgFor-2')(format=".")
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'directives-ngFor-3')
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'directives-ngFor-4')
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'directives-ngFor-5')
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'directives-ngFor-6')
+makeExample('template-syntax/dart/lib/app_component.html', 'NgFor-3')(format=".")
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'directives-ngFor-7')
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'star-template')
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'star-template-ngIf-1')
+makeExample('template-syntax/dart/lib/app_component.html', 'Template-1')(format=".")
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'star-template-ngIf-2')
+makeExample('template-syntax/dart/lib/app_component.html', 'Template-2')(format=".")
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'star-template-ngIf-3')
// Changed from RED to ORANGE, since this isn't so dire a situation in Dart.
.callout.is-important
header Remember the brackets!
:marked
Dont make the mistake of writing `ngIf="currentHero"`!
That syntax assigns the *string* value "currentHero" to `ngIf`,
which won't work because `ngIf` expects a bool. **[QUESTION: Did I get that right?]**
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'star-template-ngFor-1')
+makeExample('template-syntax/dart/lib/app_component.html', 'NgFor-2')(format=".")
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'star-template-ngFor-2')
+makeExample('template-syntax/dart/lib/app_component.html', 'Template-3')(format=".")
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'star-template-ngFor-3')
+makeExample('template-syntax/dart/lib/app_component.html', 'Template-4')(format=".")
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'star-template-ngFor-4')
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'local-vars-1')
+makeExample('template-syntax/dart/lib/app_component.html', 'Template-4')(format=".")
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'local-vars-2')
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'local-vars-refs')
+makeExample('template-syntax/dart/lib/app_component.html', 'var-phone')(format=".")
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'local-vars-value')
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'local-vars-form-1')
+makeExample('template-syntax/dart/lib/app_component.html', 'var-form')(format=".")
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'local-vars-form-2')
+makeExample('template-syntax/dart/lib/app_component.html', 'var-form-a')(format=".")
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'local-vars-form-3')
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'inputs-outputs-1')
+makeExample('template-syntax/dart/lib/app_component.html', 'io-1')(format=".")
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'inputs-outputs-2')
+makeExample('template-syntax/dart/lib/app_component.html', 'io-2')(format=".")
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'inputs-outputs-3')
+makeExample('template-syntax/dart/lib/hero_detail_component.dart', 'input-output-1')(format=".")
:marked
.l-sub-section
:marked
Alternatively, we can identify members in the `inputs` and `outputs` arrays
of the directive metadata, as in this example:
+makeExample('template-syntax/dart/lib/hero_detail_component.dart', 'input-output-2')(format=".")
<br>
:marked
We can specify an input/output property either with a decorator or in a metadata array.
Don't do both!
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'inputs-outputs-4')
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'inputs-outputs-5')
+makeExample('template-syntax/dart/lib/app_component.html', 'my-click')(format=".")
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'inputs-outputs-6')
+makeExample('template-syntax/dart/lib/my_click_directive.dart', 'my-click-output-1')(format=".")
.l-sub-section
:marked
We can also alias property names in the `inputs` and `outputs` arrays.
We write a colon-delimited (`:`) string with
the directive property name on the *left* and the public alias on the *right*:
+makeExample('template-syntax/dart/lib/my_click_directive.dart', 'my-click-output-2')(format=".")
<a id="expression-operators"></a>
.l-main-section
:marked
## Template expression operators
The template expression language employs a subset of Dart syntax supplemented with a few special operators
for specific scenarios. We'll cover two of these operators: _pipe_ and _Elvis_.
.callout.is-helpful
header Dart difference: ?. is a Dart operator
:marked
The Elvis operator (`?.`) is part of the Dart language.
It's considered a template expression operator because
Angular 2 supports `?.` even in TypeScript and JavaScript apps.
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'expression-operators-pipe-1')
+makeExample('template-syntax/dart/lib/app_component.html', 'pipes-1')(format=".")
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'expression-operators-pipe-2')
+makeExample('template-syntax/dart/lib/app_component.html', 'pipes-2')(format=".")
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'expression-operators-pipe-3')
+makeExample('template-syntax/dart/lib/app_component.html', 'pipes-3')(format=".")
//
NOTE: Intentionally omit discussion of the json pipe.
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'expression-operators-pipe-4')
+makeExample('template-syntax/dart/lib/app_component.html', 'pipes-json')(format=".")
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'expression-operators-elvis-1')
+makeExample('template-syntax/dart/lib/app_component.html', 'elvis-2')(format=".")
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'expression-operators-elvis-2')
+makeExample('template-syntax/dart/lib/app_component.html', 'elvis-1')(format=".")
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'expression-operators-elvis-3')
// +includeShared('../../../ts/latest/guide/template-syntax.jade', 'expression-operators-elvis-4')
:marked
Dart throws an exception, and so does Angular:
code-example(format="" language="html").
EXCEPTION: The null object does not have a getter 'firstName'.
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'expression-operators-elvis-5')
+makeExample('template-syntax/dart/lib/app_component.html', 'elvis-4')(format=".")
//
NOTE: Intentionally skip ugly null checking you wouldn't do in Dart.
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'expression-operators-elvis-6')
+makeExample('template-syntax/dart/lib/app_component.html', 'elvis-5')(format=".")
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'expression-operators-elvis-7')
:marked
This approach has merit but can be cumbersome, especially if the property path is long.
Imagine guarding against a null somewhere in a long property path such as `a.b.c.d`.
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'expression-operators-elvis-8')
+makeExample('template-syntax/dart/lib/app_component.html', 'elvis-6')(format=".")
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'expression-operators-elvis-9')
+includeShared('../../../ts/latest/guide/template-syntax.jade', 'summary')

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