我整理了一个简单的例子。
<body ng-app="app" ng-controller="myTestCntrl">
<input type="button" ng-click="increaseCounter()" value="Click me" /> clicked: {{counter}z} times<br/>
<input type="button" ng-click="pauseWatcher()" value="{{watcherBtnText}}" /> watched: {{internalCounter}} times<br/>
<strong>Number of $$watchers in $scope:</strong> {{$$watchers.length}}
<script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/angularjs/1.2.16/angular.js"></script>
<script type="text/javascript">
angular.module('app', [])
.controller('myTestCntrl', function myTestCntrl($scope) {
$scope.counter = 0;
$scope.pauseWatching = false;
$scope.watcherBtnText = 'Pause';
$scope.internalCounter = -1;
$scope.increaseCounter = function() {
$scope.counter++;
};
var listenerFn = function() {
if ($scope.pauseWatching) {
namedWatcher();
} else {
$scope.internalCounter++;
};
}
var namedWatcher = $scope.$watch('counter', listenerFn);
$scope.pauseWatcher = function() {
if ($scope.pauseWatching) {
$scope.watcherBtnText = 'Pause';
$scope.pauseWatching = false;
$scope.internalCounter--;
namedWatcher = $scope.$watch('counter', listenerFn);
} else {
$scope.watcherBtnText = 'Continue';
$scope.pauseWatching = true;
namedWatcher();
};
}
});
</script>
</body>
jsfiddle 上的演示:http: //jsfiddle.net/BuriB/63sND/