AngularJs 观察窗口变量 [英] AngularJs watch window variable

问题描述

在 angularJs 中可以查看全局变量吗?

In angularJs is possible to watch a global variable?

我从旧代码中设置了一个 window.test 变量，然后我需要观察该变量以了解它是否存在.

I set a window.test variable from legacy code, then I need to watch that variable to know if it exists.

我尝试过类似的东西

$window.$watch("test" , function(n,o){
    //some code here...
}

推荐答案

有点.如果您包含 Angular $window 服务，则可以(如文档中所述，这比直接访问 window 更安全):

Somewhat. You can if you include the Angular $window service (which is safer, as explained in the docs, than accessing window directly):

app.controller('myCtrl', function ($scope,$window) {...}

然后使用 watch 函数作为 $watch<的第一个参数/a> 像这样:

And then use a watch function as the first parameter to your $watch like so:

$scope.$watch(
    function () {
        return $window.test 
    }, function(n,o){
        console.log("changed ",n);
    }
);

演示小提琴

但请注意，$watch 不会执行，直到某些东西触发 Angular 执行 $digest.一种可能的方法是将遗留代码包装在 $scope.$apply 中，或者在遗留代码执行后触发 $digest.这里有一些很好的文档.

But note that the $watch won't execute until something triggers Angular to do a $digest. One possible way to do that is to wrap your legacy code in a $scope.$apply or trigger a $digest once the legacy code has exectuted. Here's some good documentation on this.

基本上，每当在 angular 之外发生更改时(例如，这是 jQuery 导致更改时的常见问题)，必须有一些东西告诉 Angular 去查看是否有更改.这是 Angular 保持合理性能的一种方式.

Basically whenever a change happens outside of angular (for instance this is a common issue when jQuery causes the change) something has to tell Angular to go see if something changed. It's one way Angular maintains reasonable performance.

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