forked from mohsennn/styleguide
-
Notifications
You must be signed in to change notification settings - Fork 0
/
angularjs-google-style.html
393 lines (316 loc) · 13.7 KB
/
angularjs-google-style.html
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0//EN" "https://www.w3.org/TR/REC-html40/strict.dtd">
<html>
<head>
<META http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<base target="_blank">
<link rel="stylesheet" type="text/css" href="styleguide.css">
<script src="https://google-code-prettify.googlecode.com/svn/loader/run_prettify.js"></script>
<script language="javascript" src="/eng/doc/devguide/include/styleguide.js"></script>
<title>Google's AngularJS Style Guide</title>
<style type="text/css"><!--
th { background-color: #ddd; }
//--></style>
</head>
<body onload="prettyPrint();initStyleGuide();">
<h1 class="external">An AngularJS Style Guide for Closure Users at Google</h1>
<p class="external">This is the external version of a document that was primarily written for Google
engineers. It describes a recommended style for AngularJS apps that use Closure, as used
internally at Google. Members of the broader AngularJS community should feel free to apply
(or not apply) these recommendations, as relevant to their own use cases.</p>
<p class="external">This document describes style for AngularJS apps in google3. This guide
supplements and extends the <a href="https://google.github.io/styleguide/jsguide.html">
Google JavaScript Style Guide</a>.
</p>
<p><b>Style Note</b>: Examples on the AngularJS external webpage, and many external apps, are
written in a style that freely uses closures, favors functional inheritance, and does not often use
<a class="external"
href="https://github.com/google/closure-compiler/wiki/Types-in-the-Closure-Type-System">
JavaScript types</a>. Google follows a more rigorous Javascript style to support JSCompiler
optimizations and large code bases - see the javascript-style mailing list.
This is not an Angular-specific issue, and is not discussed further in this style guide.
(But if you want further reading:
<a href="http://martinfowler.com/bliki/Lambda.html">Martin Fowler on closures</a>,
<a href="http://jibbering.com/faq/notes/closures/">much longer description</a>, appendix A of the
<a href="https://books.google.com/books/about/Closure_The_Definitive_Guide.html?id=p7uyWPcVGZsC">
closure book</a> has a good description of inheritance patterns and why it prefers
pseudoclassical,
<a href="https://books.google.com/books/about/JavaScript.html?id=PXa2bby0oQ0C">
Javascript, the Good Parts</a> as a counter.)</p>
<h5>1 Angular Language Rules</h5>
<ul>
<li> <a target="_self" href="#googprovide">Manage dependencies with Closure's goog.require and
goog.provide</a>
<li> <a target="_self" href="#modules"> Modules</a>
<li> <a target="_self" href="#moduledeps"> Modules should reference other modules using the
"name" property</a>
<li> <a target="_self" href="#externs">Use the provided Angular externs file</a>
<li> <a target="_self" href="#compilerflags">JSCompiler Flags</a>
<li> <a target="_self" href="#controllers">Controllers and Scopes</a>
<li> <a target="_self" href="#directives">Directives</a>
<li> <a target="_self" href="#services">Services</a>
</ul>
<h5>2 Angular Style Rules</h5>
<ul>
<li><a target="_self" href="#dollarsign">Reserve $ for Angular properties and services
</a>
<li><a target="_self" href="#customelements">Custom elements.</a>
</ul>
<h5>3 Angular Tips, Tricks, and Best Practices</h5>
<ul>
<li><a target="_self" href="#testing">Testing</a>
<li><a target="_self" href="#appstructure">Consider using the Best Practices for App Structure</a>
<li><a target="_self" href="#scopeinheritance">Be aware of how scope inheritance works</a>
<li><a target="_self" href="#nginject">Use @ngInject for easy dependency injection compilation</a>
</ul>
<h5><a target="_self" href="#bestpractices">4 Best practices links and docs</a></h5>
<h2>1 Angular Language Rules</h2>
<h3 id="googprovide">Manage dependencies with Closure's goog.require and goog.provide</h3>
<p>Choose a namespace for your project, and use goog.provide and goog.require.</p>
<pre class="prettyprint lang-js">
goog.provide('hello.about.AboutCtrl');
goog.provide('hello.versions.Versions');
</pre>
<p><b>Why?</b>
Google BUILD rules integrate nicely with closure provide/require.</p>
<h3 id="modules">Modules</h3>
<p>Your main application module should be in your root client directory. A module should never be
altered other than the one where it is defined.</p>
<p>Modules may either be defined in the same file as their components (this works well for a module
that contains exactly one service) or in a separate file for wiring pieces together.</p>
<p><b>Why?</b>
A module should be consistent for anyone that wants to include it as a reusable component.
If a module can mean different things depending on which files are included, it is not consistent.
</p>
<h3 id="moduledeps">
Modules should reference other modules using the Angular Module's "name" property
</h3>
<p>For example:</p>
<pre class="prettyprint lang-js">
// file submodulea.js:
goog.provide('my.submoduleA');
my.submoduleA = angular.module('my.submoduleA', []);
// ...
// file app.js
goog.require('my.submoduleA');
Yes: my.application.module = angular.module('hello', [my.submoduleA.name]);
<font color="red">
No: my.application.module = angular.module('hello', ['my.submoduleA']);
</font></pre>
<p><b>Why?</b>
Using a property of my.submoduleA prevents Closure presubmit failures complaining that the file is
required but never used. Using the .name property avoids duplicating strings.</p>
<h3 id="externs">Use a common externs file</h3>
<p>This maximally allows the JS compiler to enforce type safety in the presence of externally
provided types from Angular, and means you don't have to worry about Angular vars being obfuscated
in a confusing way. </p>
<p>Note to readers outside Google: the current externs file is located in an internal-to-Google
directory, but an example can be found on github <a href="https://github.com/angular/angular.js/pull/4722">
here</a>.</p>
<h3 id="compilerflags">JSCompiler Flags</h3>
<p><b>Reminder</b>: According to the JS style guide, customer facing code must be compiled.</p>
<p><b>Recommended</b>: Use the JSCompiler (the closure compiler that works with js_binary by
default) and ANGULAR_COMPILER_FLAGS_FULL from //javascript/angular/build_defs/build_defs for
your base flags.
</p>
<p>Note - if you are using @export for methods, you will need to add the compiler flag</p>
<pre>
"--generate_exports",
</pre>
<p>If you are using @export for properties, you will need to add the flags:</p>
<pre>
"--generate_exports",
"--remove_unused_prototype_props_in_externs=false",
"--export_local_property_definitions",
</pre>
<h3 id="controllers">Controllers and Scopes</h3>
<p>Controllers are classes. Methods should be defined on MyCtrl.prototype.</p>
<p>Google Angular applications should use the <b>'controller as'</b> style to export the controller
onto the scope. This is fully implemented in Angular 1.2 and can be mimicked in pre-Angular 1.2
builds.
</p>
<p>Pre Angular 1.2, this looks like:</p>
<pre class="prettyprint lang-js">
/**
* Home controller.
*
* @param {!angular.Scope} $scope
* @constructor
* @ngInject
* @export
*/
hello.mainpage.HomeCtrl = function($scope) {
/** @export */
$scope.homeCtrl = this; // This is a bridge until Angular 1.2 controller-as
/**
* @type {string}
* @export
*/
this.myColor = 'blue';
};
/**
* @param {number} a
* @param {number} b
* @export
*/
hello.mainpage.HomeCtrl.prototype.add = function(a, b) {
return a + b;
};
</pre>
<p>And the template:</p>
<pre>
<div ng-controller="hello.mainpage.HomeCtrl"/>
<span ng-class="homeCtrl.myColor">I'm in a color!</span>
<span>{{homeCtrl.add(5, 6)}}</span>
</div>
</pre>
<p>After Angular 1.2, this looks like:</p>
<pre class="prettyprint lang-js">
/**
* Home controller.
*
* @constructor
* @ngInject
* @export
*/
hello.mainpage.HomeCtrl = function() {
/**
* @type {string}
* @export
*/
this.myColor = 'blue';
};
/**
* @param {number} a
* @param {number} b
* @export
*/
hello.mainpage.HomeCtrl.prototype.add = function(a, b) {
return a + b;
};
</pre>
<p>If you are compiling with property renaming, expose properties and methods using the @export
annotation. Remember to @export the constructor as well.</p>
<p>And in the template:</p>
<pre>
<div ng-controller="hello.mainpage.HomeCtrl as homeCtrl"/>
<span ng-class="homeCtrl.myColor">I'm in a color!</span>
<span>{{homeCtrl.add(5, 6)}}</span>
</div>
</pre>
<p><b>Why?</b>
Putting methods and properties directly onto the controller, instead of building up a scope
object, fits better with the Google Closure class style. Additionally, using 'controller as'
makes it obvious which controller you are accessing when multiple controllers apply to an element.
Since there is always a '.' in the bindings, you don't have to worry about prototypal inheritance
masking primitives.</p>
<h3 id="directives">Directives</h3>
<p>All DOM manipulation should be done inside directives. Directives should be kept small and use
composition. Files defining directives should goog.provide a static function which returns the
directive definition object.</p>
<pre class="prettyprint lang-js">
goog.provide('hello.pane.paneDirective');
/**
* Description and usage
* @return {angular.Directive} Directive definition object.
*/
hello.pane.paneDirective = function() {
// ...
};
</pre>
<p><b>Exception</b>: DOM manipulation may occur in services for DOM elements disconnected from the
rest of the view, e.g. dialogs or keyboard shortcuts.</p>
<h3 id="services">Services</h3>
<p>Services registered on the module with <code>module.service</code> are classes.
Use <code>module.service</code> instead of <code>module.provider</code> or
<code>module.factory</code> unless you need to do initialization beyond just creating a
new instance of the class.</p>
<pre class="prettyprint lang-js">
/**
* @param {!angular.$http} $http The Angular http service.
* @constructor
*/
hello.request.Request = function($http) {
/** @type {!angular.$http} */
this.http_ = $http;
};
hello.request.Request.prototype.get = function() {/*...*/};
</pre>
<p>In the module:</p>
<pre class="prettyprint lang-js">
module.service('request', hello.request.Request);
</pre>
<h2>2 Angular Style Rules</h2>
<h3 id="dollarsign">Reserve $ for Angular properties and services</h3>
<p>Do not use $ to prepend your own object properties and service identifiers. Consider this style
of naming reserved by AngularJS and jQuery.</p>
<p>Yes:</p>
<pre class="prettyprint lang-js">
$scope.myModel = { value: 'foo' }
myModule.service('myService', function() { /*...*/ });
var MyCtrl = function($http) {this.http_ = $http;};
</pre>
<p><font color="red">No:</font></p>
<pre class="prettyprint">
$scope.$myModel = { value: 'foo' } // BAD
$scope.myModel = { $value: 'foo' } // BAD
myModule.service('$myService', function() { ... }); // BAD
var MyCtrl = function($http) {this.$http_ = $http;}; // BAD
</pre>
<p><b>Why?</b>
It's useful to distinguish between Angular / jQuery builtins and things you add yourself.
In addition, $ is not an acceptable character for variables names in the JS style guide.
</p>
<h3 id="customelements">Custom elements</h3>
<p>For custom elements (e.g. <code><ng-include src="template"></ng-include></code>), IE8
requires special support (html5shiv-like hacks) to enable css styling. Be aware of this
restriction in apps targeting old versions of IE.</p>
<h2>3 Angular Tips, Tricks, and Best Practices</h2>
<p>These are not strict style guide rules, but are placed here as reference for folks getting
started with Angular at Google.</p>
<h3 id="testing">Testing</h3>
<p>Angular is designed for test-driven development.</p>
<p>The recommended unit testing setup is Jasmine + Karma (though you could use closure tests
or js_test)</p>
<p>Angular provides easy adapters to load modules and use the injector in Jasmine tests.
<ul>
<li><a href = "https://docs.angularjs.org/api/angular.mock.module">module</a>
<li><a href="https://docs.angularjs.org/api/angular.mock.inject">inject</a>
</ul>
</p>
<h3 id="appstructure">Consider using the Best Practices for App Structure</h3>
<p>
This <a href="https://docs.google.com/document/d/1XXMvReO8-Awi1EZXAXS4PzDzdNvV6pGcuaF4Q9821Es/pub">directory structure doc</a> describes how to structure your application with controllers in
nested subdirectories and all components (e.g. services and directives) in a 'components' dir.
</p>
<h3 id="scopeinheritance">Be aware of how scope inheritance works</h3>
<p>See <a href="https://github.com/angular/angular.js/wiki/Understanding-Scopes#wiki-JSproto">
The Nuances of Scope Prototypal Inheritance</a></p>
<h3 id="nginject">Use @ngInject for easy dependency injection compilation</h3>
<p>This removes the need to add <code>myCtrl['$inject'] = ...</code> to prevent minification from
messing up Angular's dependency injection.</p>
<p>Usage:</p>
<pre class="prettyprint lang-js">
/**
* My controller.
* @param {!angular.$http} $http
* @param {!my.app.myService} myService
* @constructor
* @export
* @ngInject
*/
my.app.MyCtrl = function($http, myService) {
//...
};
</pre>
<h2 id="bestpractices">4 Best practices links and docs</h2>
<ul>
<li><a href="https://github.com/angular/angular.js/wiki/Best-Practices">
Best Practices</a> from Angular on GitHub</li>
<li><a href="https://www.youtube.com/watch?v=ZhfUv0spHCY">
Meetup video</a> (not Google specific)</li>
</ul>
<address>
Last modified Feb 07 2013
</address>
</body>
<html>