得到什么在默认情况下角加入到$范围。$$观察？什么触发$摘要？ [英] What gets added to $scope.$$watchers by default in Angular? And what triggers $digests?
问题描述
我在读自创AngularJS 以及对如何体面的理解 $范围， $观看和 $消化的工作。我理解它是如何工作的，当你添加自己的 $手表键，并呼吁自己的 $摘要。不过，我感到困惑，究竟是默认发生的 的
-
什么被添加到
$范围。$$观察家默认？你把$范围一切吗？一切你分配一个NG-模型来？都？别的东西吗？ -
和确切时间做
$摘要默认情况下被触发？输入领域的变化？与NG-模型输入域？其他？
一些使用通用指令 $观看 / $ watchCollection / $ watchGroup 内部：
- NG-模型
- NG-绑定/ {{}}
- NG-秀＆放大器; NG-隐藏
- 纳克级
- NG-重复
- NG-如果
- NG-开关
- NG-包括
需要注意的是建立一个双向绑定的只有一个是 NG-模型（范围 - >查看＆放大器;查看 - >范围内）。
其他人建立了一个单向绑定（范围 - >视图）。
只要暴露在例如控制器的 $范围的东西会的不可以添加一个观察者。
例如，下面将不会导致观察者被添加
angular.module（'对myApp'，[]）。控制器（'控制'，功能MyCtrl（$范围）{
$ scope.value = 1;
}）;
连同
＆LT;机身NG-应用=对myAppNG控制器=控制器＆GT;
＆LT; /身体GT;
但是，如果你用下面的一个观察者取代HTML将被添加：
＆LT;机身NG-应用=对myAppNG控制器=控制器＆GT;
＆LT; DIV＆GT; {{}值}＆LT; / DIV＆GT;
＆LT; /身体GT;
在消化周期触发一些常见的场景：
- 当
NG-点击评估 - 当
NG-模型的变化（例如在输入打字的时候） - 在
$ HTTP服务 - 在
$超时和$间隔
请注意，有之间的一个很大的区别 $适用和 $消化：
调用范围。$摘要（）将执行只在范围和其子的观察家。
调用范围。$适用（）将触发 $消化在 $ rootScope ，这意味着所有范围会遍历所有观察家执行。
$适用还接受前pression作为参数。这当然pression将一个try-catch语句中进行评估，任何异常将被传递到 $ exceptionHandler的服务。
$摘要不接受任何参数。
通常你只能叫 $消化而不是 $适用当你追逐微的优化，真正知道你在做什么。
I'm reading Build Your Own AngularJS and have a decent understanding of how $scopes, $watch and $digest work. I understand how it works when you add your own $watches and and call your own $digests. However, I'm confused about what exactly is happening by default.
What gets added to
$scope.$$watchersby default? Everything you put on$scope? Everything you assign anng-modelto? Both? Something else?And when exactly do
$digestsget triggered by default? Input field changes? Input fields withng-models? Other?
Some of the common directives that use $watch / $watchCollection / $watchGroup internally:
- ng-model
- ng-bind / {{ }}
- ng-show & ng-hide
- ng-class
- ng-repeat
- ng-if
- ng-switch
- ng-include
Note that the only one that sets up a two-way binding is ng-model (scope -> view & view -> scope).
The others set up a one-way binding (scope -> view).
Simply exposing something on for example a controller´s $scope will not add a watcher.
For example, the following will not result in a watcher being added:
angular.module('myApp', []).controller('Controller', function MyCtrl($scope) {
$scope.value = 1;
});
Together with:
<body ng-app="myApp" ng-controller="Controller">
</body>
But if you replace the HTML with the following one watcher will be added:
<body ng-app="myApp" ng-controller="Controller">
<div>{{value}}</div>
</body>
Some common scenarios when the digest cycle is triggered:
- When
ng-clickis evaluated - When
ng-modelchanges (for example when typing in an input) - By the
$httpservice - In
$timeoutand$interval
Note that there is one big difference between $apply and $digest:
Calling scope.$digest() will execute the watchers only on that scope and its children.
Calling scope.$apply() will trigger $digest on the $rootScope, which means all the scopes will be traversed and all watchers executed.
$apply also accepts an expression as an argument. This expression will be evaluated inside a try-catch statement and any exception will be passed on to the $exceptionHandler service.
$digest does not accept any arguments.
Usually you only call $digest instead of $apply when you are chasing micro optimizations and really know what you are doing.
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