如何连续监视范围变量直到更新

Question

在angular.js中有$ watch来查看更新的范围变量。但是我能做些什么，例如在变量更新之前执行函数

Answer 1

观察价值变化

var watchVar = $scope.$watch('value', function(newValue , oldValue){
  if(newValue!=oldValue){
  //value changed remove watch
  watchVar();
 }
});

Answer 2

   //try this (please inject $interval service to your controller)
    var execueMe = function () {
        //your stuff
    }

    $interval(execueMe, 3000); //will trigger every 3 seconds