AngularJS: The Performance Parts

Transcript

1. None

2. AngularJS the performance parts @toddmotto

3. » Lead Engineer @ Mozio » Google Developer Expert »

   @toddmotto » Blog at toddmotto.com

4. Topics » New features (1.2 - 1.3+) » Generic changes

   » Perf features » Performance driven Angular » $digest loop/$$watchers/$$asyncQueue » Quick wins, tips and tricks » Structure practices, advanced techniques

5. 1.2 to 1.3+

6. 1.2 to 1.3+ generic changes

7. » IE8 support dropped » DOM manipulation » ~4.3 times

   faster » 73% less garbage » $digest loop » ~3.5 times faster » 78% less garbage » 400+ bug fixes

8. 1.2 to 1.3+ perf features

9. » One-time bind syntax » ngModelOptions » bindToController property »

   ngModel.$validators » ngMessage/ngMessages » strictDI » $applyAsync in $http » Disable debug info

10. one time bindings <p>{{ ::vm.name }}</p> <p ng-bind="::vm.name"></p> <div ng-if="::vm.user.loggedIn"></div>

    <div ng-class="::{ loggedIn: vm.user.loggedIn }"></div> <ul> <li ng-repeat="user in ::vm.users"> {{ ::user.name }} </li> </ul>

11. one time bindings » Defined with :: » $watched until

    not "undefined" » $$watcher is unbound » Will not update upon Model changes » One-time, not one-way » Great for single static rendering

12. ng-Model-Options <!-- updateOn --> <input type="text" ng-model="vm.model" ng-model-options="{ updateOn: 'default

    blur' }">

13. ng-Model-Options <!-- debounce: - example will debounce 250ms when typing

    - example will update model immediately on "blur" --> <input type="text" ng-model="vm.model" ng-model-options="{ updateOn: 'default blur', debounce: { 'default': 250, 'blur': 0 } }">

14. ng-Model-Options // directive controller function FooDirCtrl() { // undo model

    changes if (condition) { this.model.$rollbackViewValue(); } }

15. ng-Model-Options » Fine tune how Model updates are done »

    Define event types » Add debounce to delay Model synchronisation » e.g. { debounce: 250 } = $digest ~250ms » $rollbackViewValue for undoing model changes

16. bindToController // directive controller function FooDirCtrl() { this.bar = {};

    this.doSomething = function doSomething(arg) { this.bar.foobar = arg; }.bind(this); }

17. bindToController // directive controller function FooDirCtrl($scope) { this.bar = {};

    this.doSomething = function doSomething(arg) { this.bar.foobar = arg; // reference the isolate property $scope.name = arg.prop; }.bind(this); }

18. bindToController function fooDirective() { return { ... scope: {}, bindToController:

    { name: '=' }, ... }; }

19. bindToController // directive controller function FooDirCtrl() { this.bar = {};

    this.doSomething = function doSomething(arg) { this.bar.foobar = arg; // reference the isolate property this.name = arg.prop; }.bind(this); }

20. bindToController » Used with "controllerAs" (class-like) » Binds isolate props

    to the Controller instance » No $scope » $scope remains "special use only" » Not used for data » Used for $watch/$on/etc

21. ngModel.$validators // old school function visaValidator() { var VISA_REGEXP =

    /^4[0-9]{12}(?:[0-9]{3})?$/; function link($scope, element, attrs, ngModel) { ngModel.$parsers.unshift(function (value) { var valid = VISA_REGEXP.test(value); ngModel.$setValidity('visaValidator', valid); return valid ? value : undefined; }); } return { require : 'ngModel', link : link }; } angular.module('app').directive('visaValidator', visaValidator);

22. ngModel.$validators // new school function visaValidator() { var VISA_REGEXP =

    /^4[0-9]{12}(?:[0-9]{3})?$/; function link($scope, element, attrs, ngModel) { ngModel.$validators.visaValidator = function (value) { return VISA_REGEXP.test(value); // Boolean }; } return { require : 'ngModel', link : link }; } angular.module('app').directive('visaValidator', visaValidator);

23. ngModel.$validators <form name="myForm"> <label> <input type="text" ng-model="myForm.card" visa-validator> <div ng-if="myForm.myPassword.$error.visaValidator">

    Not a valid VISA format! </div> </label> </form>

24. ngModel.$validators » ngModel.$validators Object » Instead of $parsers/$formatters » Return

    a Boolean from the bound function » Use with the $error Object in the View

25. ngMessage/ngMessages <form name="myForm"> <label> Enter email: <input type="text" ng-model="field" name="myField"

    required ng-minlength="5" ng-maxlength="100"> </label> <div ng-messages="myForm.myField.$error" role="alert"> <div ng-message="required"> You did not enter a field </div> <div ng-message="minlength, maxlength"> Your email must be between 5 and 100 characters long </div> </div> </form>

26. ngMessage/ngMessages » Conditional validation » ngModel.$error Object » Acts like

    a switch case

27. strictDI <div ng-app="myApp" ng-strict-di> <!-- app --> </div>

28. strictDI // implicit annotation function SomeService($scope, $timeout) { //... }

    angular .module('app') .factory('SomeService', SomeService);

29. strictDI function SomeService($scope, $timeout) { //... } // Array annotations

    SomeService.$inject = ['$scope', '$timeout']; angular .module('app') .factory('SomeService', SomeService);

30. strictDI » Runs the application's $injector in strict mode »

    Throws an error on Services using implicit annotations » Use ng-annotate to automate this process

31. $applyAsync with $http function config($httpProvider) { $httpProvider.useApplyAsync(true); } angular .module('app',

    []) .config(config); More: blog.thoughtram.io/angularjs/2015/01/14/exploring-angular-1.3-speed-up-with-applyAsync.html

32. $applyAsync with $http » Enables $applyAsync to be used with

    $http » Schedules an async $apply for batched requests » For requests that resolve within ~10ms » Pushes into $$asyncQueue » Single $digest

33. Disable debug info function config($compileProvider) { $compileProvider.debugInfoEnabled(false); } angular .module('app',

    []) .config(config);

34. Disable debug info <!-- enabled --> <div ng-controller="MainCtrl as vm"

    class="ng-scope ng-binding"> <my-directive class="ng-isolate-scope"> // content </my-directive> </div> <!-- disabled --> <div ng-controller="MainCtrl as vm"> <my-directive> // content </my-directive> </div>

35. Disable debug info » Disable in production for performance boosts

    » Removes $scope references on elements » Doesn't add classes to DOM nodes with binding info » Enable in console with angular.reloadWithDebugInfo();

36. Performance driven Angular

37. Understand what impacts performance before you code

38. Under the hood: $digest

39. $digest fundamentals » $digest loop » $$watchers ($watch) » $$asyncQueue

    ($evalAsync)
40. None
41. None
42. None
43. None
44. None
45. None
46. None
47. None

48. $digest: $digest loop » Triggered by $scope.$apply / built-in events

    » Iterates $$watchers Array on $scope » If model value is different from last calculated then corresponding listener executes » Exits loop, Angular loops again (10 max) » Repaints DOM (View expressions updated)

49. $digest: $$watchers » View events/bindings {{ foo }} » Angular

    adds a watch to the $watch list » Only $watched if bound in the View » Dirty checked in the $digest loop » Minimise use of $$watchers / avoid if possible

50. $digest: $$asyncQueue » $evalAsync » Runs first in $digest »

    May run $digest again to flush $$asyncQueue

51. track by Scenarios: * Large DOM lists * Slow DOM

    updates * $digests blocking UI thread (lagging)

52. track by <!-- before --> <ul> <li ng-repeat="user in vm.users">

    {{ user.name }} </li> </ul>

53. track by <!-- after --> <ul> <li ng-repeat="user in vm.users

    track by user.id"> {{ user.name }} </li> </ul>

54. track by » Minimal DOM repaints (only what's changed) »

    Uses Object references instead of Angular hashes

55. ng-if / switch vs ng-show / hide <!-- ng-show -->

    <ul ng-show="vm.exposeNav"> <li ng-repeat="menu in vm.menus"></li> </ul> <!-- ng-if --> <ul ng-if="vm.exposeNav"> <li ng-repeat="menu in vm.menus"></li> </ul>

56. ng-if / switch vs ng-show / hide » ng-if/switch reconstruct

    the DOM » ng-if/switch for less frequent/heavier rendering » ng-show/hide toggle "ng-hide" class » ng-show/hide for more frequent/lighter rendering » ng-show/hide less performant due to $$watchers (when hidden)

57. ng-bind over {{ handlebars }} <!-- handlebars --> <p>{{ vm.username

    }}</p> <!-- ng-bind --> <p ng-bind="vm.username"></p> <!-- perf example --> <p> Welcome <span ng-bind="vm.username"></span> to Facebook </p>

58. ng-bind over {{ handlebars }} » No DOM flicker (invisible

    bindings) with ng-bind » Significantly faster » ng-perf.com/2014/10/30/tip-4-ng-bind-is-faster- than-expression-bind-and-one-time-bind » Lesser need for ng-cloak » Angular won't evaluate entire text content

59. $apply or $digest? // forces a $rootScope.$digest(); $scope.$apply(); // forces

    a [current $scope].$digest(); $scope.$digest();

60. $apply or $digest? » $scope certainties » Prevent a full

    $rootScope.$digest() if you're certain only child $scopes need updating » Improve performance by not forcing a full $rootScope.$digest » $scope.$digest runs on current and child $scopes » $scope.$apply triggers $rootScope.$digest call

61. $destroy unbinding function myFunction () { // handle element clicks

    } // bind element.on('click', myFunction); // unbind $scope.$on('$destroy', function () { element.off('click', myFunction); });

62. $destroy unbinding » Remove event listeners that may cause memory

    leaks » DOM nodes that are destroyed » Manually unbind by listening to $destroy » $scope.$on events are automatically removed

63. Deep $watch vs $watchCollection var prop = [{...},{...},{...},{...}]; $scope.$watch('prop', function

    (newValue, oldValue) { }, true); $scope.$watchCollection('prop', function (newValue, oldValue) { });

64. Deep $watch vs $watchCollection » Deep $watch uses deep Object

    tree comparison (expensive) » $watchCollection goes only one level deep » Shallow reference of all top level items » Try not to use either unless you have to » Not as testable » Signs of bad architecture » Litter Controllers

65. avoiding DOM filters <!-- vm.date = 1444175093303 --> <p>{{ vm.date

    | date: 'dd-MM-yyyy' }}</p>

66. avoiding DOM filters function SomeCtrl($filter) { // date passed in

    elsewhere var time = 1444175093303; // Parsed in JS before bound to the DOM this.parsedDate = $filter('date')(time, 'dd-MM-yyyy'); } angular .module('app') .controller('SomeCtrl', SomeCtrl);

67. avoiding DOM filters <p>{{ vm.parsedDate }}</p>

68. avoiding DOM filters » DOM filters run twice per $digest

    » Preprocess in a Controller » Bind parsed value to the View

69. Takeaways » Understand the $digest loop » Investigate the performance

    side of each Directive/API you use » Consider using JavaScript over DOM bindings where possible ($filter etc.) » Check Angular's GitHub repo for changelogs/ releases

70. Thank you @toddmotto speakerdeck.com/toddmotto

71. None