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JavaScript AngularJS An Introduction to Two-Way Data Binding Two-Way Binding: watchers

Posted by Sharon Kearney
Sharon Kearney
8,662 Points

create watcher

code challenge help

$scope.$watch ('user.id' function (getUserData) { if (newId) { api.saveId ($scope.userId); }

});

})

app.js 
angular.module('myApp', [])
.controller('myController', function ($scope, $http) {
  $scope.user = {name: 'Alex', id: 123};

  getUserData = function (id) {
    console.log('Getting user with ID: ' + id);
  }

  $scope.$watch('user.id' function (getUserData) {
    if (newId) {
      api.saveId ($scope.userId);

    };    
});

});
index.html 
<!DOCTYPE html>
<html ng-app="myApp">
<head>
  <title>Angular.js</title>
  <script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.3.2/angular.min.js"></script>
  <script src="app.js"></script>
</head>
<body ng-controller="myController">

  <input type="text" ng-model="user.id" />

</body>
</html>

1 Answer

Andrew Kiernan
Andrew Kiernan
26,892 Points
Andrew Kiernan
Andrew Kiernan
26,892 Points

Hi Sharon!

The benefit of the $scope.$watch is that you don't need to check the property to see if it changed, the callback function you pass into $scope.$watch will only be executed when the property you are watching changes. It will also pass the changed property into the callback. With this in mind, you can just pass the function you want to execute into the 2nd parameter of the $watch method.

$scope.$watch('user.id', getUserData);

Hope that helps! Let me know if you have any questions.

-Andrew