Class Component

The collection of functions, keyed by name, available on this ActionHandler as action targets.

These functions will be invoked when a matching {{action}} is triggered from within a template and the application's current route is this route.

Actions can also be invoked from other parts of your application via ActionHandler#send.

The actions hash will inherit action handlers from the actions hash defined on extended parent classes or mixins rather than just replace the entire hash, e.g.:

import Mixin from '@ember/object/mixin';

export default Mixin.create({
  actions: {
    displayBanner(msg) {
      // ...
    }
  }
});

import Route from '@ember/routing/route';
import CanDisplayBanner from '../mixins/can-display-banner';

export default Route.extend(CanDisplayBanner, {
  actions: {
    playMusic() {
      // ...
    }
  }
});

// `WelcomeRoute`, when active, will be able to respond
// to both actions, since the actions hash is merged rather
// then replaced when extending mixins / parent classes.
this.send('displayBanner');
this.send('playMusic');

Within a Controller, Route or Component's action handler, the value of the this context is the Controller, Route or Component object:

import Route from '@ember/routing/route';

export default Route.extend({
  actions: {
    myAction() {
      this.controllerFor("song");
      this.transitionTo("other.route");
      ...
    }
  }
});

It is also possible to call this._super(...arguments) from within an action handler if it overrides a handler defined on a parent class or mixin:

Take for example the following routes:

import Mixin from '@ember/object/mixin';

export default Mixin.create({
  actions: {
    debugRouteInformation() {
      console.debug("It's a-me, console.debug!");
    }
  }
});

import Route from '@ember/routing/route';
import DebugRoute from '../mixins/debug-route';

export default Route.extend(DebugRoute, {
  actions: {
    debugRouteInformation() {
      // also call the debugRouteInformation of mixed in DebugRoute
      this._super(...arguments);

      // show additional annoyance
      window.alert(...);
    }
  }
});

Bubbling

By default, an action will stop bubbling once a handler defined on the actions hash handles it. To continue bubbling the action, you must return true from the handler:

Router.map(function() {
  this.route("album", function() {
    this.route("song");
  });
});

import Route from '@ember/routing/route';

export default Route.extend({
  actions: {
    startPlaying: function() {
    }
  }
});

import Route from '@ember/routing/route';

export default Route.extend({
  actions: {
    startPlaying() {
      // ...

      if (actionShouldAlsoBeTriggeredOnParentRoute) {
        return true;
      }
    }
  }
});

The WAI-ARIA role of the control represented by this view. For example, a button may have a role of type 'button', or a pane may have a role of type 'alertdialog'. This property is used by assistive software to help visually challenged users navigate rich web applications.

The full list of valid WAI-ARIA roles is available at: https://www.w3.org/TR/wai-aria/#roles_categorization

A list of properties of the view to apply as attributes. If the property is a string value, the value of that string will be applied as the value for an attribute of the property's name.

The following example creates a tag like <div priority="high" />.

import Component from '@ember/component';

export default Component.extend({
   attributeBindings: ['priority'],
   priority: 'high'
 });

If the value of the property is a Boolean, the attribute is treated as an HTML Boolean attribute. It will be present if the property is true and omitted if the property is false.

The following example creates markup like <div visible />.

import Component from '@ember/component';

export default Component.extend({
   attributeBindings: ['visible'],
   visible: true
 });

If you would prefer to use a custom value instead of the property name, you can create the same markup as the last example with a binding like this:

import Component from '@ember/component';

export default Component.extend({
   attributeBindings: ['isVisible:visible'],
   isVisible: true
 });

This list of attributes is inherited from the component's superclasses, as well.

A list of properties of the view to apply as class names. If the property is a string value, the value of that string will be applied as a class name.

// Applies the 'high' class to the view element
import Component from '@ember/component';
Component.extend({
  classNameBindings: ['priority'],
  priority: 'high'
});

If the value of the property is a Boolean, the name of that property is added as a dasherized class name.

// Applies the 'is-urgent' class to the view element
import Component from '@ember/component';
Component.extend({
  classNameBindings: ['isUrgent'],
  isUrgent: true
});

If you would prefer to use a custom value instead of the dasherized property name, you can pass a binding like this:

// Applies the 'urgent' class to the view element
import Component from '@ember/component';
Component.extend({
  classNameBindings: ['isUrgent:urgent'],
  isUrgent: true
});

If you would like to specify a class that should only be added when the property is false, you can declare a binding like this:

// Applies the 'disabled' class to the view element
import Component from '@ember/component';
Component.extend({
  classNameBindings: ['isEnabled::disabled'],
  isEnabled: false
});

This list of properties is inherited from the component's superclasses as well.

Standard CSS class names to apply to the view's outer element. This property automatically inherits any class names defined by the view's superclasses as well.

Defines the properties that will be concatenated from the superclass (instead of overridden).

By default, when you extend an Ember class a property defined in the subclass overrides a property with the same name that is defined in the superclass. However, there are some cases where it is preferable to build up a property's value by combining the superclass' property value with the subclass' value. An example of this in use within Ember is the classNames property of Component from @ember/component.

Here is some sample code showing the difference between a concatenated property and a normal one:

import EmberObject from '@ember/object';

const Bar = EmberObject.extend({
  // Configure which properties to concatenate
  concatenatedProperties: ['concatenatedProperty'],

  someNonConcatenatedProperty: ['bar'],
  concatenatedProperty: ['bar']
});

const FooBar = Bar.extend({
  someNonConcatenatedProperty: ['foo'],
  concatenatedProperty: ['foo']
});

let fooBar = FooBar.create();
fooBar.get('someNonConcatenatedProperty'); // ['foo']
fooBar.get('concatenatedProperty'); // ['bar', 'foo']

This behavior extends to object creation as well. Continuing the above example:

let fooBar = FooBar.create({
  someNonConcatenatedProperty: ['baz'],
  concatenatedProperty: ['baz']
})
fooBar.get('someNonConcatenatedProperty'); // ['baz']
fooBar.get('concatenatedProperty'); // ['bar', 'foo', 'baz']

Adding a single property that is not an array will just add it in the array:

let fooBar = FooBar.create({
  concatenatedProperty: 'baz'
})
view.get('concatenatedProperty'); // ['bar', 'foo', 'baz']

Using the concatenatedProperties property, we can tell Ember to mix the content of the properties.

In Component the classNames, classNameBindings and attributeBindings properties are concatenated.

This feature is available for you to use throughout the Ember object model, although typical app developers are likely to use it infrequently. Since it changes expectations about behavior of properties, you should properly document its usage in each individual concatenated property (to not mislead your users to think they can override the property in a subclass).

Returns the current DOM element for the view.

The HTML id of the component's element in the DOM. You can provide this value yourself but it must be unique (just as in HTML):

{{my-component elementId="a-really-cool-id"}}

<MyComponent @elementId="a-really-cool-id" />

If not manually set a default value will be provided by the framework. Once rendered an element's elementId is considered immutable and you should never change it. If you need to compute a dynamic value for the elementId, you should do this when the component or element is being instantiated:

export default Component.extend({
  init() {
    this._super(...arguments);

    var index = this.get('index');
    this.set('elementId', `component-id${index}`);
  }
});

Destroyed object property flag.

if this property is true the observers and bindings were already removed by the effect of calling the destroy() method.

Destruction scheduled flag. The destroy() method has been called.

The object stays intact until the end of the run loop at which point the isDestroyed flag is set.

Layout can be used to wrap content in a component.

Defines the properties that will be merged from the superclass (instead of overridden).

By default, when you extend an Ember class a property defined in the subclass overrides a property with the same name that is defined in the superclass. However, there are some cases where it is preferable to build up a property's value by merging the superclass property value with the subclass property's value. An example of this in use within Ember is the queryParams property of routes.

Here is some sample code showing the difference between a merged property and a normal one:

import EmberObject from '@ember/object';

const Bar = EmberObject.extend({
  // Configure which properties are to be merged
  mergedProperties: ['mergedProperty'],

  someNonMergedProperty: {
    nonMerged: 'superclass value of nonMerged'
  },
  mergedProperty: {
    page: { replace: false },
    limit: { replace: true }
  }
});

const FooBar = Bar.extend({
  someNonMergedProperty: {
    completelyNonMerged: 'subclass value of nonMerged'
  },
  mergedProperty: {
    limit: { replace: false }
  }
});

let fooBar = FooBar.create();

fooBar.get('someNonMergedProperty');
// => { completelyNonMerged: 'subclass value of nonMerged' }
//
// Note the entire object, including the nonMerged property of
// the superclass object, has been replaced

fooBar.get('mergedProperty');
// => {
//   page: {replace: false},
//   limit: {replace: false}
// }
//
// Note the page remains from the superclass, and the
// `limit` property's value of `false` has been merged from
// the subclass.

This behavior is not available during object create calls. It is only available at extend time.

In Route the queryParams property is merged.

This feature is available for you to use throughout the Ember object model, although typical app developers are likely to use it infrequently. Since it changes expectations about behavior of properties, you should properly document its usage in each individual merged property (to not mislead your users to think they can override the property in a subclass).

Enables components to take a list of parameters as arguments. For example, a component that takes two parameters with the names name and age:

 import Component from '@ember/component';

 let MyComponent = Component.extend();

 MyComponent.reopenClass({
   positionalParams: ['name', 'age']
 });

 export default MyComponent;

It can then be invoked like this:

 {{my-component "John" 38}}

The parameters can be referred to just like named parameters:

 Name: {{name}}, Age: {{age}}.

Using a string instead of an array allows for an arbitrary number of parameters:

 import Component from '@ember/component';

 let MyComponent = Component.extend();

 MyComponent.reopenClass({
   positionalParams: 'names'
 });

 export default MyComponent;

It can then be invoked like this:

 {{my-component "John" "Michael" "Scott"}}

The parameters can then be referred to by enumerating over the list:

 {{#each names as |name|}}{{name}}{{/each}}

Tag name for the view's outer element. The tag name is only used when an element is first created. If you change the tagName for an element, you must destroy and recreate the view element.

By default, the render buffer will use a <div> tag for views.

If the tagName is '', the view will be tagless, with no outer element. Component properties that depend on the presence of an outer element, such as classNameBindings and attributeBindings, do not work with tagless components. Tagless components cannot implement methods to handle events, and their element property has a null value.