angularjs: $watch two variables and do something if only one changes

Question

I have a situation in which I want to monitor a specific variable.

$scope.$watch('action', function() { /* do something */ }

However, I only want to do something if $scope.id didn't change (if $scope.action changes it is possible that $scope.id has changed too.)

The only solution I can think of is

$scope.$watch('action', function() { 
    if(idHasChanhed === false){
        /* do something */ 
    }
    idHasChanged = false;
});
$scope.$watch('id', function() { idHasChanged = true }

However, I was wondering if angular has a better solution than this, and I don't know if this solution will always work ( is the order in which the $watches are executed random !?)

EpokK · Answer 1 · 2014-02-10T14:29:21.350

4

My solution :

$scope.$watch('[action,id]', function() { 
   // called when action or id changed
});

Info : The string concatenation action + id will fail.

edited Feb 10 '14 at 14:29

answered Feb 10 '14 at 14:19

EpokK

38,062
9
61
69

1

Hmm, I've implemented it now and I get the following error: `Error: [$rootScope:infdig] 10 $digest() iterations reached. Aborting!` It gets triggered all the time without the data changing – Jeanluca Scaljeri Feb 10 '14 at 14:33
Turns out that my question is a duplicate of [this](http://stackoverflow.com/questions/16729965/how-to-watch-multiple-variable-change-in-angular) question – Jeanluca Scaljeri Feb 10 '14 at 15:08

score 0 · Answer 2 · answered Feb 26 '16 at 06:23

0

var action,id;   // variables you need to watch
 $scope.$watch('action + id', function() { 
       // actions
    });

answered Feb 26 '16 at 06:23

Ashish Yadav

11
5

score 0 · Answer 3 · answered Feb 26 '16 at 06:24

$watchGroup This function is introduced in Angular1.3. This works the same as $watch() function except that the first parameter is an array of expressions to watch.

Use $watchGroup

$scope.$watchGroup(['action', 'id'], function(newVal, oldVal) {
    //write your code here
});

angularjs: $watch two variables and do something if only one changes

3 Answers3