javascript中的setTimeout与angularjs中的$ timeout服务之间的差异 [英] difference between setTimeout in javascript and $timeout service in angularjs
问题描述
我是角度框架的新手。这是我的场景，我想在一段时间后更改我的$ scope.variable所以我使用javascript setTimeout 方法。
Iam new to angular framework.Here is my scenario where, I want to change my $scope.variable after a period of time so i used javascript setTimeout method.
$scope.variable='Previous';
setTimeout(function(){
$scope.variable='NEXT';
},3000);
此代码对我不起作用。我使用 $ apply（）来使这段代码工作。
This code doesn't worked for me. I used $apply() to make this code work.
后来我才知道角度本身有一个$ timeout服务执行相同的工作。
Later i came to know that angular itself has a $timeout service which does the same work.
$scope.variable='Previous';
$timeout(function () {
$scope.variable='NEXT';
}, 2000);
如何比较 $ timeout 的性能？使用javascript服务 setTimeout ??
How can i compare performance of $timeout service with javascript setTimeout??
为什么我们应该使用 $ timeout 而不是 setTimeout ??
Why we should use $timeout instead of setTimeout??
请给我一些使用它的例子和理由，其中显示了性能。
Please give me some examples and reasons to use it, which shows the performance.
谢谢:)
推荐答案
在某些情况下一个人需要执行某种超时操作，我们经常使用JavaScript的 setTimeout（）函数来实现这一点。
There are some cases where one needs to perform some sort of timeout operation and we frequently achieve this using JavaScript's setTimeout() function.
但是，如果我们在AngularJS应用程序中使用 setTimeout（），我们还需要使用 $ scope。$ apply（）来确保对范围的任何更改都将反映在其他位置（即视图中的数据绑定）。
However, if we use setTimeout() in an AngularJS application we also need to use $scope.$apply() to ensure that any changes to the scope will be reflected elsewhere (i.e. data-bound in a view).
AngularJS 为此提供了一个方便的包装： $ timeout（） - 它执行 $ apply（）我们没有必须 $ apply 更改。
AngularJS provides a handy wrapper for this: $timeout() - it does the $apply() for which we don't have to $apply the changes.
关于效果。
如果您使用 $ timeout 来创建本质上是间隔的内容，则不要使用它。如果您的应用程序很大，那么 $ apply 也会触发 $ digest 循环，您可能不希望它发生，肯定会降低性能。
If you're using $timeout to create what is essentially an interval, then don't use it. If your application is large then $apply will also trigger a $digest cycle which you may not really want it to happen, it will surely decrease the performance.
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