Watching an array of objects in AngularJS with assigned indices

Question

Watching an array of objects in AngularJS with assigned indices

I'm seeking guidance on how to utilize Angular watch with an array of objects.

Here is an example array $scope.chartSeries containing objects like this:

[{"location": {values}, "id":"serie-1", "meter":{values}, "name": "seriename", "data":[{1,2,4,5,7,4,6}]}]

These objects are used to create a linechart using highcharts.

I am trying to implement a watch on this array so that I can detect any changes to its values along with the index and the changed value itself.

I've explored various watch options but none seem to cater to my requirements. Any suggestions?

javascript angularjs highcharts

Answer 1

Answer №1

When utilizing ng-repeat to render and modify your array, consider utilizing the ng-change directive and passing a $index parameter to it.

Here's an example:

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

Alternatively, you can employ $watch and handle newValue and oldValue parameters.

$scope.$watch('array', function (newValue, oldValue) {
   for(var i = 0; i < newValue.length; i++) {
      if(newValue[i].location != oldValue[i].location)
        var indexOfChangedItem = i;
        //do something
   }
}, true);

Answer 2

When utilizing ng-repeat to render and modify your array, consider utilizing the ng-change directive and passing a $index parameter to it.

Here's an example:

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

Alternatively, you can employ $watch and handle newValue and oldValue parameters.

$scope.$watch('array', function (newValue, oldValue) {
   for(var i = 0; i < newValue.length; i++) {
      if(newValue[i].location != oldValue[i].location)
        var indexOfChangedItem = i;
        //do something
   }
}, true);

Answer 3

Answer №2

To implement the $watchGroup(watchExpressions, listener) function, simply follow these steps:

For example, you can set it up like this:

$scope.chartSeries = [{"location": {values}, "id":"serie-1", "meter":{values}, "name": "seriename", "data":[{1,2,4,5,7,4,6}]};

$scope.$watchCollection('chartSeries ', randomFunction(var) {
//code
});

Alternatively, you can use watch for individual values in an array to track which ones have changed.

Answer 4

To implement the $watchGroup(watchExpressions, listener) function, simply follow these steps:

For example, you can set it up like this:

$scope.chartSeries = [{"location": {values}, "id":"serie-1", "meter":{values}, "name": "seriename", "data":[{1,2,4,5,7,4,6}]};

$scope.$watchCollection('chartSeries ', randomFunction(var) {
//code
});

Alternatively, you can use watch for individual values in an array to track which ones have changed.

Watching an array of objects in AngularJS with assigned indices

Answer №1

Answer №2

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