Trouble arises with the extent of a unique directive's scope

Question

Trouble arises with the extent of a unique directive's scope

Greetings! I currently have a custom directive that looks like this:

mainApp.directive('myMenu',function(){
        return {
            restrict : 'E',
            scope :{menuItems : "=menuItems"},
            compile: function(element, attributes) {
                var linkFunction = function($scope, element, attributes){
                    for (i = 0;i<$scope.menuItems.length;i++){
                         element.append('<li><a href="#home">'+$scope.menuItems[i].name+'</a></li>');
                    }
                }
                return linkFunction;
            }

        }
    });

I am implementing it in my HTML page as shown below:

<my-menu menuItems="menuItems"></my-menu>

However, when I check the console, I encounter an error message stating TypeError: Cannot read property 'length' of undefined

javascript angularjs

Answer 1

Answer №1

One issue that may arise is during the linking phase where the menu items might not have been loaded yet, resulting in $scope.menuItems being undefined.

An alternative approach would be:

var mainApp = angular.module('my-app', [], function() {})

mainApp.controller('AppController', function($scope) {
  $scope.menuItems = [{
    name: 'one'
  }, {
    name: 'two'
  }, {
    name: 'three'
  }, {
    name: 'four'
  }];
})

mainApp.directive('myMenu', function() {
  return {
    restrict: 'E',
    scope: {
      menuItems: "="
    },
    template: '<ul><li ng-repeat="item in menuItems">{{item.name}}<a href="#home"></a></li></ul>'
  }
});

<script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/angularjs/1.3.15/angular.js"></script>

<div ng-app="my-app" ng-controller="AppController">
  <my-menu menu-items="menuItems"></my-menu>
</div>

If using a template is not feasible, then consider this alternative:

var mainApp = angular.module('my-app', [], function() {})

mainApp.controller('AppController', function($scope) {
  $scope.menuItems = [{
    name: 'one'
  }, {
    name: 'two'
  }, {
    name: 'three'
  }, {
    name: 'four'
  }];
})

mainApp.directive('myMenu', function() {
  return {
    restrict: 'E',
    scope: {
      menuItems: "=menuItems"
    },
    link: function($scope, element, attributes) {
      $scope.$watch('menuItems', function(value) {
        element.empty();
        angular.forEach(value, function(item) {
          element.append('<li><a href="#home">' + item.name + '</a></li>');
        });
      });
    }

  }
});

<script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/angularjs/1.3.15/angular.js"></script>

<div ng-app="my-app" ng-controller="AppController">
  <my-menu menu-items="menuItems"></my-menu>
</div>

Answer 2

One issue that may arise is during the linking phase where the menu items might not have been loaded yet, resulting in $scope.menuItems being undefined.

An alternative approach would be:

var mainApp = angular.module('my-app', [], function() {})

mainApp.controller('AppController', function($scope) {
  $scope.menuItems = [{
    name: 'one'
  }, {
    name: 'two'
  }, {
    name: 'three'
  }, {
    name: 'four'
  }];
})

mainApp.directive('myMenu', function() {
  return {
    restrict: 'E',
    scope: {
      menuItems: "="
    },
    template: '<ul><li ng-repeat="item in menuItems">{{item.name}}<a href="#home"></a></li></ul>'
  }
});

<script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/angularjs/1.3.15/angular.js"></script>

<div ng-app="my-app" ng-controller="AppController">
  <my-menu menu-items="menuItems"></my-menu>
</div>

If using a template is not feasible, then consider this alternative:

var mainApp = angular.module('my-app', [], function() {})

mainApp.controller('AppController', function($scope) {
  $scope.menuItems = [{
    name: 'one'
  }, {
    name: 'two'
  }, {
    name: 'three'
  }, {
    name: 'four'
  }];
})

mainApp.directive('myMenu', function() {
  return {
    restrict: 'E',
    scope: {
      menuItems: "=menuItems"
    },
    link: function($scope, element, attributes) {
      $scope.$watch('menuItems', function(value) {
        element.empty();
        angular.forEach(value, function(item) {
          element.append('<li><a href="#home">' + item.name + '</a></li>');
        });
      });
    }

  }
});

<script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/angularjs/1.3.15/angular.js"></script>

<div ng-app="my-app" ng-controller="AppController">
  <my-menu menu-items="menuItems"></my-menu>
</div>

Answer 3

Answer №2

The problem arose from the naming convention I utilized - for example, in a directive, 'menu-items' should be used instead of 'menuItems'. The issue was resolved by changing 'menuItems' to 'menu'.

Answer 4

The problem arose from the naming convention I utilized - for example, in a directive, 'menu-items' should be used instead of 'menuItems'. The issue was resolved by changing 'menuItems' to 'menu'.

Answer 5

Answer №3

Call

$scope.$eval(attributes.menuItems)

within the compile function to retrieve the menu items

Answer 6

Call

$scope.$eval(attributes.menuItems)

within the compile function to retrieve the menu items

Trouble arises with the extent of a unique directive's scope

Answer №1

Answer №2

Answer №3

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