The console is showing an 'undefined' return value for the $index variable in Angular

Question

The console is showing an 'undefined' return value for the $index variable in Angular

Hi there,

I've encountered a problem with some code I wrote, and I'm hoping someone can help me figure out what's going on.

This particular snippet of code is supposed to run when the menu buttons are clicked.

$scope.show = function($index){
    console.log($index);
};

However, when I check the console log, it's always returning 'undefined'.

If anyone has any insights or suggestions, I would really appreciate the help.

You can view the JS bin for reference: https://jsbin.com/keteji/edit?html,js,console,output

Any assistance you can provide would be greatly valued.

Thank you in advance!

javascript angularjs

Answer 1

Answer №1

$index represents the iterator offset of the repeated element, accessible within each template instance in ng-repeat

If your menu list is stored as dataArray, you can utilize ng-repeat to display the iterations in the view

Give this a try:

var app = angular.module('angularApp',[]);

app.controller('AppController',['$scope',function($scope){
  $scope.dataJson = dataArray;
//   console.log($scope);
  
  
  $scope.show = function($index){
    alert($index);
  };
  
  
  $('.nav li').click(function(){
    $('.nav li').removeClass('active');
    $(this).addClass('active');
  });
  
}]);

var dataArray =[
  {
    "id":1,
    "name":"Home",
    "visible":true
  },
  {
    "id":2,
    "name":"Profile",
    "visible":false
  },
  {
    "id":3,
    "name":"Messages",
    "visible":false
  }
];

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.0/jquery.min.js"></script>
<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.2.23/angular.min.js"></script>
<body ng-app="angularApp">
  <div ng-controller="AppController">
    
    <ul class="nav nav-pills">
      <li role="presentation" ng-repeat="d in dataJson" ng-click="show($index)"><a href>{{d.name}}</a></li>
      
    </ul>

    <div class="row">
      
      <div class="col-md-12" ng-repeat="pages in dataJson">
        <h3 ng-show="pages.visible">
          {{pages.name}}
        </h3>
      </div>  
      
      
    </div>
  
  </div>
  
  
</body>

Answer 2

$index represents the iterator offset of the repeated element, accessible within each template instance in ng-repeat

If your menu list is stored as dataArray, you can utilize ng-repeat to display the iterations in the view

Give this a try:

var app = angular.module('angularApp',[]);

app.controller('AppController',['$scope',function($scope){
  $scope.dataJson = dataArray;
//   console.log($scope);
  
  
  $scope.show = function($index){
    alert($index);
  };
  
  
  $('.nav li').click(function(){
    $('.nav li').removeClass('active');
    $(this).addClass('active');
  });
  
}]);

var dataArray =[
  {
    "id":1,
    "name":"Home",
    "visible":true
  },
  {
    "id":2,
    "name":"Profile",
    "visible":false
  },
  {
    "id":3,
    "name":"Messages",
    "visible":false
  }
];

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.0/jquery.min.js"></script>
<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.2.23/angular.min.js"></script>
<body ng-app="angularApp">
  <div ng-controller="AppController">
    
    <ul class="nav nav-pills">
      <li role="presentation" ng-repeat="d in dataJson" ng-click="show($index)"><a href>{{d.name}}</a></li>
      
    </ul>

    <div class="row">
      
      <div class="col-md-12" ng-repeat="pages in dataJson">
        <h3 ng-show="pages.visible">
          {{pages.name}}
        </h3>
      </div>  
      
      
    </div>
  
  </div>
  
  
</body>

Answer 3

Answer №2

$index is a special attribute within the ngRepeat directive scope.

It's not accessible within controller scopes.

Answer 4

$index is a special attribute within the ngRepeat directive scope.

It's not accessible within controller scopes.

The console is showing an 'undefined' return value for the $index variable in Angular

Answer №1

Answer №2

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