naomib@google.com | 3fcaf64 | 2014-02-13 00:50:10 +0000 | [diff] [blame] | 1 | |
Ackermann Yuriy | 7969290 | 2016-04-01 21:41:34 +1300 | [diff] [blame] | 2 | <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0//EN" "https://www.w3.org/TR/REC-html40/strict.dtd"> |
naomib@google.com | 3fcaf64 | 2014-02-13 00:50:10 +0000 | [diff] [blame] | 3 | <html> |
| 4 | <head> |
| 5 | <META http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> |
| 6 | <base target="_blank"> |
naomib@google.com | 2349571 | 2014-02-13 01:07:04 +0000 | [diff] [blame] | 7 | <link rel="stylesheet" type="text/css" href="styleguide.css"> |
naomib@google.com | a5eb0c5 | 2014-02-23 16:10:08 +0000 | [diff] [blame] | 8 | <script src="https://google-code-prettify.googlecode.com/svn/loader/run_prettify.js"></script> |
naomib@google.com | 3fcaf64 | 2014-02-13 00:50:10 +0000 | [diff] [blame] | 9 | <script language="javascript" src="/eng/doc/devguide/include/styleguide.js"></script> |
| 10 | <title>Google's AngularJS Style Guide</title> |
| 11 | <style type="text/css"><!-- |
| 12 | th { background-color: #ddd; } |
| 13 | //--></style> |
| 14 | </head> |
| 15 | <body onload="prettyPrint();initStyleGuide();"> |
| 16 | <h1 class="external">An AngularJS Style Guide for Closure Users at Google</h1> |
| 17 | |
| 18 | <p class="external">This is the external version of a document that was primarily written for Google |
| 19 | engineers. It describes a recommended style for AngularJS apps that use Closure, as used |
| 20 | internally at Google. Members of the broader AngularJS community should feel free to apply |
| 21 | (or not apply) these recommendations, as relevant to their own use cases.</p> |
| 22 | |
| 23 | <p class="external">This document describes style for AngularJS apps in google3. This guide |
Stephen Hicks | 8f25442 | 2016-11-02 17:17:28 -0700 | [diff] [blame] | 24 | supplements and extends the <a href="https://google.github.io/styleguide/jsguide.html"> |
naomib@google.com | 3fcaf64 | 2014-02-13 00:50:10 +0000 | [diff] [blame] | 25 | Google JavaScript Style Guide</a>. |
| 26 | </p> |
| 27 | |
| 28 | <p><b>Style Note</b>: Examples on the AngularJS external webpage, and many external apps, are |
| 29 | written in a style that freely uses closures, favors functional inheritance, and does not often use |
| 30 | <a class="external" |
Stephen Hicks | 8f25442 | 2016-11-02 17:17:28 -0700 | [diff] [blame] | 31 | href="https://github.com/google/closure-compiler/wiki/Types-in-the-Closure-Type-System"> |
naomib@google.com | 3fcaf64 | 2014-02-13 00:50:10 +0000 | [diff] [blame] | 32 | JavaScript types</a>. Google follows a more rigorous Javascript style to support JSCompiler |
| 33 | optimizations and large code bases - see the javascript-style mailing list. |
| 34 | This is not an Angular-specific issue, and is not discussed further in this style guide. |
| 35 | (But if you want further reading: |
| 36 | <a href="http://martinfowler.com/bliki/Lambda.html">Martin Fowler on closures</a>, |
| 37 | <a href="http://jibbering.com/faq/notes/closures/">much longer description</a>, appendix A of the |
Ackermann Yuriy | 7969290 | 2016-04-01 21:41:34 +1300 | [diff] [blame] | 38 | <a href="https://books.google.com/books/about/Closure_The_Definitive_Guide.html?id=p7uyWPcVGZsC"> |
naomib@google.com | 3fcaf64 | 2014-02-13 00:50:10 +0000 | [diff] [blame] | 39 | closure book</a> has a good description of inheritance patterns and why it prefers |
| 40 | pseudoclassical, |
Ackermann Yuriy | 7969290 | 2016-04-01 21:41:34 +1300 | [diff] [blame] | 41 | <a href="https://books.google.com/books/about/JavaScript.html?id=PXa2bby0oQ0C"> |
naomib@google.com | 3fcaf64 | 2014-02-13 00:50:10 +0000 | [diff] [blame] | 42 | Javascript, the Good Parts</a> as a counter.)</p> |
| 43 | |
| 44 | <h5>1 Angular Language Rules</h5> |
| 45 | <ul> |
| 46 | <li> <a target="_self" href="#googprovide">Manage dependencies with Closure's goog.require and |
| 47 | goog.provide</a> |
| 48 | <li> <a target="_self" href="#modules"> Modules</a> |
| 49 | <li> <a target="_self" href="#moduledeps"> Modules should reference other modules using the |
| 50 | "name" property</a> |
| 51 | <li> <a target="_self" href="#externs">Use the provided Angular externs file</a> |
| 52 | <li> <a target="_self" href="#compilerflags">JSCompiler Flags</a> |
| 53 | <li> <a target="_self" href="#controllers">Controllers and Scopes</a> |
| 54 | <li> <a target="_self" href="#directives">Directives</a> |
| 55 | <li> <a target="_self" href="#services">Services</a> |
| 56 | </ul> |
| 57 | <h5>2 Angular Style Rules</h5> |
| 58 | <ul> |
| 59 | <li><a target="_self" href="#dollarsign">Reserve $ for Angular properties and services |
| 60 | </a> |
| 61 | <li><a target="_self" href="#customelements">Custom elements.</a> |
| 62 | </ul> |
| 63 | <h5>3 Angular Tips, Tricks, and Best Practices</h5> |
| 64 | <ul> |
| 65 | <li><a target="_self" href="#testing">Testing</a> |
| 66 | <li><a target="_self" href="#appstructure">Consider using the Best Practices for App Structure</a> |
| 67 | <li><a target="_self" href="#scopeinheritance">Be aware of how scope inheritance works</a> |
| 68 | <li><a target="_self" href="#nginject">Use @ngInject for easy dependency injection compilation</a> |
| 69 | </ul> |
| 70 | |
| 71 | <h5><a target="_self" href="#bestpractices">4 Best practices links and docs</a></h5> |
| 72 | |
| 73 | <h2>1 Angular Language Rules</h2> |
| 74 | |
| 75 | <h3 id="googprovide">Manage dependencies with Closure's goog.require and goog.provide</h3> |
| 76 | <p>Choose a namespace for your project, and use goog.provide and goog.require.</p> |
| 77 | <pre class="prettyprint lang-js"> |
| 78 | goog.provide('hello.about.AboutCtrl'); |
| 79 | goog.provide('hello.versions.Versions'); |
| 80 | </pre> |
| 81 | |
| 82 | <p><b>Why?</b> |
| 83 | Google BUILD rules integrate nicely with closure provide/require.</p> |
| 84 | |
| 85 | <h3 id="modules">Modules</h3> |
| 86 | |
| 87 | <p>Your main application module should be in your root client directory. A module should never be |
| 88 | altered other than the one where it is defined.</p> |
| 89 | |
| 90 | <p>Modules may either be defined in the same file as their components (this works well for a module |
| 91 | that contains exactly one service) or in a separate file for wiring pieces together.</p> |
| 92 | |
| 93 | <p><b>Why?</b> |
| 94 | A module should be consistent for anyone that wants to include it as a reusable component. |
| 95 | If a module can mean different things depending on which files are included, it is not consistent. |
| 96 | </p> |
| 97 | |
| 98 | <h3 id="moduledeps"> |
| 99 | Modules should reference other modules using the Angular Module's "name" property |
| 100 | </h3> |
| 101 | |
| 102 | <p>For example:</p> |
| 103 | |
| 104 | <pre class="prettyprint lang-js"> |
| 105 | // file submodulea.js: |
| 106 | goog.provide('my.submoduleA'); |
| 107 | |
| 108 | my.submoduleA = angular.module('my.submoduleA', []); |
| 109 | // ... |
| 110 | |
| 111 | // file app.js |
| 112 | goog.require('my.submoduleA'); |
| 113 | |
| 114 | Yes: my.application.module = angular.module('hello', [my.submoduleA.name]); |
| 115 | <font color="red"> |
| 116 | No: my.application.module = angular.module('hello', ['my.submoduleA']); |
| 117 | </font></pre> |
| 118 | |
| 119 | <p><b>Why?</b> |
| 120 | Using a property of my.submoduleA prevents Closure presubmit failures complaining that the file is |
| 121 | required but never used. Using the .name property avoids duplicating strings.</p> |
| 122 | |
naomib@google.com | 544e0db | 2014-02-13 21:15:54 +0000 | [diff] [blame] | 123 | <h3 id="externs">Use a common externs file</h3> |
naomib@google.com | 3fcaf64 | 2014-02-13 00:50:10 +0000 | [diff] [blame] | 124 | |
| 125 | <p>This maximally allows the JS compiler to enforce type safety in the presence of externally |
| 126 | provided types from Angular, and means you don't have to worry about Angular vars being obfuscated |
naomib@google.com | 544e0db | 2014-02-13 21:15:54 +0000 | [diff] [blame] | 127 | in a confusing way. </p> |
naomib@google.com | 3fcaf64 | 2014-02-13 00:50:10 +0000 | [diff] [blame] | 128 | |
| 129 | <p>Note to readers outside Google: the current externs file is located in an internal-to-Google |
| 130 | directory, but an example can be found on github <a href="https://github.com/angular/angular.js/pull/4722"> |
| 131 | here</a>.</p> |
| 132 | |
| 133 | <h3 id="compilerflags">JSCompiler Flags</h3> |
| 134 | <p><b>Reminder</b>: According to the JS style guide, customer facing code must be compiled.</p> |
| 135 | |
| 136 | <p><b>Recommended</b>: Use the JSCompiler (the closure compiler that works with js_binary by |
| 137 | default) and ANGULAR_COMPILER_FLAGS_FULL from //javascript/angular/build_defs/build_defs for |
| 138 | your base flags. |
| 139 | </p> |
| 140 | |
| 141 | <p>Note - if you are using @export for methods, you will need to add the compiler flag</p> |
| 142 | <pre> |
| 143 | "--generate_exports", |
| 144 | </pre> |
| 145 | |
| 146 | <p>If you are using @export for properties, you will need to add the flags:</p> |
| 147 | <pre> |
| 148 | "--generate_exports", |
| 149 | "--remove_unused_prototype_props_in_externs=false", |
| 150 | "--export_local_property_definitions", |
| 151 | </pre> |
| 152 | |
| 153 | <h3 id="controllers">Controllers and Scopes</h3> |
Stephen Hicks | 8f25442 | 2016-11-02 17:17:28 -0700 | [diff] [blame] | 154 | <p>Controllers are classes. Methods should be defined on MyCtrl.prototype.</p> |
naomib@google.com | 3fcaf64 | 2014-02-13 00:50:10 +0000 | [diff] [blame] | 155 | |
| 156 | <p>Google Angular applications should use the <b>'controller as'</b> style to export the controller |
| 157 | onto the scope. This is fully implemented in Angular 1.2 and can be mimicked in pre-Angular 1.2 |
| 158 | builds. |
| 159 | </p> |
| 160 | |
| 161 | <p>Pre Angular 1.2, this looks like:</p> |
| 162 | <pre class="prettyprint lang-js"> |
| 163 | /** |
| 164 | * Home controller. |
| 165 | * |
| 166 | * @param {!angular.Scope} $scope |
| 167 | * @constructor |
| 168 | * @ngInject |
| 169 | * @export |
| 170 | */ |
| 171 | hello.mainpage.HomeCtrl = function($scope) { |
| 172 | /** @export */ |
| 173 | $scope.homeCtrl = this; // This is a bridge until Angular 1.2 controller-as |
| 174 | |
| 175 | /** |
| 176 | * @type {string} |
| 177 | * @export |
| 178 | */ |
| 179 | this.myColor = 'blue'; |
| 180 | }; |
| 181 | |
| 182 | |
| 183 | /** |
| 184 | * @param {number} a |
| 185 | * @param {number} b |
| 186 | * @export |
| 187 | */ |
| 188 | hello.mainpage.HomeCtrl.prototype.add = function(a, b) { |
| 189 | return a + b; |
| 190 | }; |
| 191 | </pre> |
| 192 | |
| 193 | <p>And the template:</p> |
| 194 | |
| 195 | <pre> |
| 196 | <div ng-controller="hello.mainpage.HomeCtrl"/> |
| 197 | <span ng-class="homeCtrl.myColor">I'm in a color!</span> |
| 198 | <span>{{homeCtrl.add(5, 6)}}</span> |
| 199 | </div> |
| 200 | </pre> |
| 201 | |
| 202 | <p>After Angular 1.2, this looks like:</p> |
| 203 | |
| 204 | <pre class="prettyprint lang-js"> |
| 205 | /** |
| 206 | * Home controller. |
| 207 | * |
| 208 | * @constructor |
| 209 | * @ngInject |
| 210 | * @export |
| 211 | */ |
| 212 | hello.mainpage.HomeCtrl = function() { |
| 213 | /** |
| 214 | * @type {string} |
| 215 | * @export |
| 216 | */ |
| 217 | this.myColor = 'blue'; |
| 218 | }; |
| 219 | |
| 220 | |
| 221 | /** |
| 222 | * @param {number} a |
| 223 | * @param {number} b |
| 224 | * @export |
| 225 | */ |
| 226 | hello.mainpage.HomeCtrl.prototype.add = function(a, b) { |
| 227 | return a + b; |
| 228 | }; |
| 229 | </pre> |
| 230 | |
| 231 | <p>If you are compiling with property renaming, expose properties and methods using the @export |
| 232 | annotation. Remember to @export the constructor as well.</p> |
| 233 | |
| 234 | <p>And in the template:</p> |
| 235 | |
| 236 | <pre> |
| 237 | <div ng-controller="hello.mainpage.HomeCtrl as homeCtrl"/> |
| 238 | <span ng-class="homeCtrl.myColor">I'm in a color!</span> |
| 239 | <span>{{homeCtrl.add(5, 6)}}</span> |
| 240 | </div> |
| 241 | </pre> |
| 242 | |
| 243 | <p><b>Why?</b> |
| 244 | Putting methods and properties directly onto the controller, instead of building up a scope |
| 245 | object, fits better with the Google Closure class style. Additionally, using 'controller as' |
| 246 | makes it obvious which controller you are accessing when multiple controllers apply to an element. |
| 247 | Since there is always a '.' in the bindings, you don't have to worry about prototypal inheritance |
| 248 | masking primitives.</p> |
| 249 | |
| 250 | <h3 id="directives">Directives</h3> |
| 251 | |
| 252 | <p>All DOM manipulation should be done inside directives. Directives should be kept small and use |
| 253 | composition. Files defining directives should goog.provide a static function which returns the |
| 254 | directive definition object.</p> |
| 255 | |
| 256 | <pre class="prettyprint lang-js"> |
| 257 | goog.provide('hello.pane.paneDirective'); |
| 258 | |
| 259 | /** |
| 260 | * Description and usage |
| 261 | * @return {angular.Directive} Directive definition object. |
| 262 | */ |
| 263 | hello.pane.paneDirective = function() { |
| 264 | // ... |
| 265 | }; |
| 266 | </pre> |
| 267 | |
| 268 | <p><b>Exception</b>: DOM manipulation may occur in services for DOM elements disconnected from the |
| 269 | rest of the view, e.g. dialogs or keyboard shortcuts.</p> |
| 270 | |
| 271 | <h3 id="services">Services</h3> |
| 272 | |
| 273 | <p>Services registered on the module with <code>module.service</code> are classes. |
| 274 | Use <code>module.service</code> instead of <code>module.provider</code> or |
| 275 | <code>module.factory</code> unless you need to do initialization beyond just creating a |
| 276 | new instance of the class.</p> |
| 277 | |
| 278 | <pre class="prettyprint lang-js"> |
| 279 | /** |
| 280 | * @param {!angular.$http} $http The Angular http service. |
| 281 | * @constructor |
| 282 | */ |
| 283 | hello.request.Request = function($http) { |
| 284 | /** @type {!angular.$http} */ |
| 285 | this.http_ = $http; |
| 286 | }; |
| 287 | |
| 288 | hello.request.Request.prototype.get = function() {/*...*/}; |
| 289 | </pre> |
| 290 | |
| 291 | <p>In the module:</p> |
| 292 | |
| 293 | <pre class="prettyprint lang-js"> |
| 294 | module.service('request', hello.request.Request); |
| 295 | </pre> |
| 296 | |
| 297 | |
| 298 | <h2>2 Angular Style Rules</h2> |
| 299 | |
| 300 | <h3 id="dollarsign">Reserve $ for Angular properties and services</h3> |
| 301 | <p>Do not use $ to prepend your own object properties and service identifiers. Consider this style |
| 302 | of naming reserved by AngularJS and jQuery.</p> |
| 303 | |
| 304 | <p>Yes:</p> |
| 305 | <pre class="prettyprint lang-js"> |
| 306 | $scope.myModel = { value: 'foo' } |
ralphj@google.com | 66b9e1b | 2014-05-21 20:28:07 +0000 | [diff] [blame] | 307 | myModule.service('myService', function() { /*...*/ }); |
naomib@google.com | 3fcaf64 | 2014-02-13 00:50:10 +0000 | [diff] [blame] | 308 | var MyCtrl = function($http) {this.http_ = $http;}; |
| 309 | </pre> |
| 310 | |
| 311 | <p><font color="red">No:</font></p> |
| 312 | <pre class="prettyprint"> |
| 313 | $scope.$myModel = { value: 'foo' } // BAD |
| 314 | $scope.myModel = { $value: 'foo' } // BAD |
| 315 | myModule.service('$myService', function() { ... }); // BAD |
| 316 | var MyCtrl = function($http) {this.$http_ = $http;}; // BAD |
| 317 | </pre> |
| 318 | |
| 319 | <p><b>Why?</b> |
| 320 | It's useful to distinguish between Angular / jQuery builtins and things you add yourself. |
| 321 | In addition, $ is not an acceptable character for variables names in the JS style guide. |
| 322 | </p> |
| 323 | |
| 324 | <h3 id="customelements">Custom elements</h3> |
| 325 | |
| 326 | <p>For custom elements (e.g. <code><ng-include src="template"></ng-include></code>), IE8 |
| 327 | requires special support (html5shiv-like hacks) to enable css styling. Be aware of this |
| 328 | restriction in apps targeting old versions of IE.</p> |
| 329 | |
| 330 | <h2>3 Angular Tips, Tricks, and Best Practices</h2> |
| 331 | |
| 332 | <p>These are not strict style guide rules, but are placed here as reference for folks getting |
| 333 | started with Angular at Google.</p> |
| 334 | |
| 335 | <h3 id="testing">Testing</h3> |
| 336 | |
| 337 | <p>Angular is designed for test-driven development.</p> |
| 338 | |
| 339 | <p>The recommended unit testing setup is Jasmine + Karma (though you could use closure tests |
| 340 | or js_test)</p> |
| 341 | |
| 342 | <p>Angular provides easy adapters to load modules and use the injector in Jasmine tests. |
| 343 | <ul> |
Ackermann Yuriy | 7969290 | 2016-04-01 21:41:34 +1300 | [diff] [blame] | 344 | <li><a href = "https://docs.angularjs.org/api/angular.mock.module">module</a> |
| 345 | <li><a href="https://docs.angularjs.org/api/angular.mock.inject">inject</a> |
naomib@google.com | 3fcaf64 | 2014-02-13 00:50:10 +0000 | [diff] [blame] | 346 | </ul> |
| 347 | </p> |
| 348 | |
naomib@google.com | 3fcaf64 | 2014-02-13 00:50:10 +0000 | [diff] [blame] | 349 | |
| 350 | <h3 id="appstructure">Consider using the Best Practices for App Structure</h3> |
naomib@google.com | c2482ee | 2014-02-13 18:27:17 +0000 | [diff] [blame] | 351 | <p> |
| 352 | 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 |
naomib@google.com | 3fcaf64 | 2014-02-13 00:50:10 +0000 | [diff] [blame] | 353 | nested subdirectories and all components (e.g. services and directives) in a 'components' dir. |
| 354 | </p> |
| 355 | |
naomib@google.com | 3fcaf64 | 2014-02-13 00:50:10 +0000 | [diff] [blame] | 356 | |
| 357 | <h3 id="scopeinheritance">Be aware of how scope inheritance works</h3> |
| 358 | |
| 359 | <p>See <a href="https://github.com/angular/angular.js/wiki/Understanding-Scopes#wiki-JSproto"> |
| 360 | The Nuances of Scope Prototypal Inheritance</a></p> |
| 361 | |
| 362 | <h3 id="nginject">Use @ngInject for easy dependency injection compilation</h3> |
| 363 | <p>This removes the need to add <code>myCtrl['$inject'] = ...</code> to prevent minification from |
| 364 | messing up Angular's dependency injection.</p> |
| 365 | |
| 366 | <p>Usage:</p> |
| 367 | <pre class="prettyprint lang-js"> |
| 368 | /** |
| 369 | * My controller. |
| 370 | * @param {!angular.$http} $http |
| 371 | * @param {!my.app.myService} myService |
| 372 | * @constructor |
| 373 | * @export |
| 374 | * @ngInject |
| 375 | */ |
| 376 | my.app.MyCtrl = function($http, myService) { |
| 377 | //... |
| 378 | }; |
| 379 | </pre> |
| 380 | |
| 381 | <h2 id="bestpractices">4 Best practices links and docs</h2> |
| 382 | |
| 383 | <ul> |
| 384 | <li><a href="https://github.com/angular/angular.js/wiki/Best-Practices"> |
| 385 | Best Practices</a> from Angular on GitHub</li> |
Ackermann Yuriy | 7969290 | 2016-04-01 21:41:34 +1300 | [diff] [blame] | 386 | <li><a href="https://www.youtube.com/watch?v=ZhfUv0spHCY"> |
naomib@google.com | 3fcaf64 | 2014-02-13 00:50:10 +0000 | [diff] [blame] | 387 | Meetup video</a> (not Google specific)</li> |
| 388 | </ul> |
| 389 | <address> |
| 390 | Last modified Feb 07 2013 |
| 391 | </address> |
| 392 | </body> |
| 393 | <html> |