Angular $scope.$watch in object of arrays

Question

$scope.testObj={};
angular.forEach(results, function (value,index) {
$scope.testObj[index]=value.arr;

console.log($scope.testObj[index]);
console.log(index);
$scope.$watch('testObj',function(newVal, oldVal) {       
        console.log(newVal, oldVal) ;  
      },true
);
})

The above code works fine (do not worry about results;it is an array). The problem lies when I am trying that:

$scope.$watch('testObj[index]',function(newVal, oldVal) {       
            console.log(newVal, oldVal) ;  
          },true
    );

I have no idea why that happens and I am getting undefined from both newVal, oldVal. How may I solve that?

By the way testObj[0] works...

you are trying to pass w variable index to a function arguments, what do you expect bro ? — ZEE
– ZEE, Commented Dec 21, 2016 at 16:18

Sajeetharan · Accepted Answer · 2016-12-21 16:28:24Z

2

Try this,

$scope.myvar = testObj[index];
$scope.$watch('myvar',function(newVal, oldVal) {       
            console.log(newVal, oldVal) ;  
          },true
);

EDIT

If you render change your array in ng-repeat, you can to use ng-change directive and pass in it $index parameter.

<div ng-repeat="arr in myvar">
   <input type="text" ng-model="arr.location" ng-change="changeValue($index)"/>
</div>

or use a loop and access using its index

$scope.$watch('myvar', function (newValue, oldValue) {
   for(var i = 0; i < newValue.length; i++) {

   }
}, true);

edited Dec 21, 2016 at 16:28

answered Dec 21, 2016 at 16:18

Sajeetharan

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2 Comments

Unknown developer Over a year ago

However, I want to keep track of all the arrays: testObj[0], testObj[1] ... The above won't do my job

Unknown developer Over a year ago

I am not using the view for that, only the controller. Is there any way for $scope.$watch to understand the first argument the way I want?

Ameur fahd · Accepted Answer · 2016-12-21 17:18:26Z

0

$watchGroup can come to your need more doc https://docs.angularjs.org/api/ng/type/$rootScope.Scope

answered Dec 21, 2016 at 17:18

Ameur fahd

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Comments

CozyAzure · Accepted Answer · 2016-12-21 17:18:50Z

0

You got the other way round. Because forEach only executed once, the $watchers inside will only watch it once and then was tore down. What you need to do is watch the collection, then put your forEach insde.

$scope.$watch('testObj', function(newVal, oldVal) {
  angular.forEach(newVal, function(value, index) {
    $scope.testObj[index] = value.arr;
    console.log($scope.testObj[index]);
    console.log(index);
  })
}, true);

answered Dec 21, 2016 at 17:18

CozyAzure

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