如何在 angularjs 中防止/解除绑定先前的 $watch [英] How to prevent/unbind previous $watch in angularjs

问题描述

我以动态方式使用 $watch，所以每次调用它都会创建另一个 $watch，而我想取消绑定以前的 $watch.

I am using $watch in dynamic way so on every call its creating another $watch while I want to unbind previous $watch.

$scope.pagination =function(){
  $scope.$watch('currentPage + numPerPage', function (newValue,oldValue) {      
    $scope.contestList = response; //getting response form $http
  }
}

我有多个标签.单击选项卡时，将调用分页函数:

I have multiple tabs. When a tab is clicked, the pagination function gets called:

$scope.ToggleTab = function(){
    $scope.pagination();
}

所以它创建了多个 $watch 并且每次我点击标签时它都会创建另一个.

so its creating multiple $watch and every time I click on tab it creates another one.

推荐答案

在添加新 watch 之前，您需要检查 watcher 是否已经存在.如果它已经存在，您可以调用 watcher() 这将从 $scope.$$watchers 数组中删除观察者.然后注册您的手表.这将确保您的手表仅创建一次.

Before adding a new watch you need to check if the watcher exists already or not. If it's already there you could just call watcher() this will remove the watcher from $scope.$$watchers array. And then register your watch. This will ensure your watch has been created only once.

var paginationWatch;
$scope.pagination = function() {
    if (paginationWatch) //check for watch exists
        paginationWatch(); //this line will destruct watch if its already there
    paginationWatch = $scope.$watch('currentPage + numPerPage', function(newValue, oldValue) {
            //getting response form $http`
            $scope.contestList = response;
        }
    });
}

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