Cannot use Object.keys function in AngularJS

Question

Cannot use Object.keys function in AngularJS

For my UI.Bootstrap accordion, I have set up the heading as follows:

<accordion-group ng=repeat="(cname, stations) in byClient">
    <accordion-heading>
        {{ cname }} <span class="pull-right"> {{ Object.keys(stations).length }} Stations</span>
    </accordion-heading>

However, when this is displayed, Object.keys(stations).length does not return any value. Strangely enough, if I place the same length call in my controller, it works and returns the expected count. Is there a reason why the method call isn't working in AngularJS?

The rest of the accordion that uses stations functions properly, indicating that the data is being populated correctly. Here is an example structure of the byClient data:

{
    "Client Name" : {
        "Station Name": [
            {...},
            {...}
        ]
    }
 }

javascript angularjs angular-ui-bootstrap

Answer 1

Answer №1

Indeed, the reason for this is that Object belongs to the window/global scope and angular is unable to evaluate that expression within its own scope. When you use Object.keys in your binding, angular attempts to evaluate it within the $scope but does not find it there. One solution could be to store a reference to Object.keys in a utility function in the rootScope so it can be accessed throughout the application.

You can achieve this by:

angular.module('yourApp',[deps...]).run(function($rootScope){
  //Add a reference to the utility methods in rootscope.
  $rootScope.Utils = {
     keys : Object.keys
  }

  //If you want the utility method accessible in isolated Scopes 
  //you would directly add the method to the prototype of rootScope constructor as shown below:

  //$rootScope.constructor.prototype.getKeys = Object.keys;

});

Then you can use it like this:

<span class="pull-right"> {{ Utils.keys(stations).length }} Stations</span>

This will be available to any child scopes except for isolated scopes. For isolated scopes (e.g., Isolated scoped directives), you would need to add the reference of Object.keys on the scope itself, or expose a method on the scope that returns the length.

Alternatively, you could create a custom filter to return the key length and use it across your app:

app.filter('keylength', function(){
  return function(input){
    if(!angular.isObject(input)){
      throw Error("Keylength filter can only be used with objects!")
    }
    return Object.keys(input).length;
  }
});

And then use it like this:

{{ stations | keylength }}

Check out the Demo here

Answer 2

Indeed, the reason for this is that Object belongs to the window/global scope and angular is unable to evaluate that expression within its own scope. When you use Object.keys in your binding, angular attempts to evaluate it within the $scope but does not find it there. One solution could be to store a reference to Object.keys in a utility function in the rootScope so it can be accessed throughout the application.

You can achieve this by:

angular.module('yourApp',[deps...]).run(function($rootScope){
  //Add a reference to the utility methods in rootscope.
  $rootScope.Utils = {
     keys : Object.keys
  }

  //If you want the utility method accessible in isolated Scopes 
  //you would directly add the method to the prototype of rootScope constructor as shown below:

  //$rootScope.constructor.prototype.getKeys = Object.keys;

});

Then you can use it like this:

<span class="pull-right"> {{ Utils.keys(stations).length }} Stations</span>

This will be available to any child scopes except for isolated scopes. For isolated scopes (e.g., Isolated scoped directives), you would need to add the reference of Object.keys on the scope itself, or expose a method on the scope that returns the length.

Alternatively, you could create a custom filter to return the key length and use it across your app:

app.filter('keylength', function(){
  return function(input){
    if(!angular.isObject(input)){
      throw Error("Keylength filter can only be used with objects!")
    }
    return Object.keys(input).length;
  }
});

And then use it like this:

{{ stations | keylength }}

Check out the Demo here

Answer 3

Answer №2

Employ this function to calculate the quantity of properties within an object:

$scope.calculateKeyLength = function (obj) {
    return Object.keys(obj).length;
}

Then utilize the following code snippet:

{{ calculateKeyLength(myObject) }}

Answer 4

Employ this function to calculate the quantity of properties within an object:

$scope.calculateKeyLength = function (obj) {
    return Object.keys(obj).length;
}

Then utilize the following code snippet:

{{ calculateKeyLength(myObject) }}

Answer 5

Answer №3

I believe that utilizing filters is the epitome of AngularJS when it comes to managing structures within template code:

angular.module('app.filters').filter('objectKeysLength', [function() {
    return function(items) {
        return Object.keys(items).length;
    };
}]);

angular.module('app.filters').filter('objectKeys', [function() {
    return function(item) {
        if (!item) return null;
        var keys = Object.keys(item);
        keys.sort();
        return keys;
    };
}]);

Answer 6

I believe that utilizing filters is the epitome of AngularJS when it comes to managing structures within template code:

angular.module('app.filters').filter('objectKeysLength', [function() {
    return function(items) {
        return Object.keys(items).length;
    };
}]);

angular.module('app.filters').filter('objectKeys', [function() {
    return function(item) {
        if (!item) return null;
        var keys = Object.keys(item);
        keys.sort();
        return keys;
    };
}]);

Answer 7

Answer №4

If you're looking for a solution for angular 2 and above, there is now the keyvalue pipe available, allowing for iteration over objects.

Answer 8

If you're looking for a solution for angular 2 and above, there is now the keyvalue pipe available, allowing for iteration over objects.

Answer 9

Answer №5

After struggling with various solutions in AngularJS 1.6, I finally found success by utilizing $window to access Object.keys. Here's the code snippet that worked for me:

$window.Object.keys({ 'x': 3, 'y': 4 })

Answer 10

After struggling with various solutions in AngularJS 1.6, I finally found success by utilizing $window to access Object.keys. Here's the code snippet that worked for me:

$window.Object.keys({ 'x': 3, 'y': 4 })

Answer 11

Answer №6

If you're looking for a solution that has proven effective, consider the following:

export class abcComponent{
    Display = Object.values;
}

When working in the HTML component file, you can implement something along these lines:

<div *ngFor="let item of Display(data)">.........</div>

Answer 12

If you're looking for a solution that has proven effective, consider the following:

export class abcComponent{
    Display = Object.values;
}

When working in the HTML component file, you can implement something along these lines:

<div *ngFor="let item of Display(data)">.........</div>

Cannot use Object.keys function in AngularJS

Answer №1

Answer №2

Answer №3

Answer №4

Answer №5

Answer №6

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