Many classes have shortcut names used when creating (instantiating) a class with a
configuration object. The shortcut name is referred to as an alias (or xtype if the
class extends Ext.Component). The alias/xtype is listed next to the class name of
applicable classes for quick reference.
Framework classes or their members may be specified as private or protected. Else,
the class / member is public. Public, protected, and private are access
descriptors used to convey how and when the class or class member should be used.
Public classes and class members are available for use by any other class or application code and may be relied upon as a stable and persistent within major product versions. Public classes and members may safely be extended via a subclass.
Protected class members are stable public members intended to be used by the
owning class or its subclasses. Protected members may safely be extended via a subclass.
Private classes and class members are used internally by the framework and are not intended to be used by application developers. Private classes and members may change or be omitted from the framework at any time without notice and should not be relied upon in application logic.
static label next to the
method name. *See Static below.Below is an example class member that we can disect to show the syntax of a class member (the lookupComponent method as viewed from the Ext.button.Button class in this case).
Let's look at each part of the member row:
lookupComponent in this example)( item ) in this example)Ext.Component in this case). This may be omitted for methods that do not
return anything other than undefined or may display as multiple possible values
separated by a forward slash / signifying that what is returned may depend on the
results of the method call (i.e. a method may return a Component if a get method calls is
successful or false if unsuccessful which would be displayed as
Ext.Component/Boolean).PROTECTED in
this example - see the Flags section below)Ext.container.Container in this example). The source
class will be displayed as a blue link if the member originates from the current class
and gray if it is inherited from an ancestor or mixed-in class.view source in the example)item : Object in the example).undefined a "Returns" section
will note the type of class or object returned and a description (Ext.Component in the
example)Available since 3.4.0 - not pictured in
the example) just after the member descriptionDefaults to: false)The API documentation uses a number of flags to further commnicate the class member's function and intent. The label may be represented by a text label, an abbreviation, or an icon.
classInstance.method1().method2().etc();false is returned from
an event handler- Indicates a framework class
- A singleton framework class. *See the singleton flag for more information
- A component-type framework class (any class within the Ext JS framework that extends Ext.Component)
- Indicates that the class, member, or guide is new in the currently viewed version
- Indicates a class member of type config
- Indicates a class member of type property
- Indicates a class member of type
method
- Indicates a class member of type event
- Indicates a class member of type
theme variable
- Indicates a class member of type
theme mixin
- Indicates that the class, member, or guide is new in the currently viewed version
Just below the class name on an API doc page is a row of buttons corresponding to the types of members owned by the current class. Each button shows a count of members by type (this count is updated as filters are applied). Clicking the button will navigate you to that member section. Hovering over the member-type button will reveal a popup menu of all members of that type for quick navigation.
Getting and setter methods that correlate to a class config option will show up in the methods section as well as in the configs section of both the API doc and the member-type menus just beneath the config they work with. The getter and setter method documentation will be found in the config row for easy reference.
Your page history is kept in localstorage and displayed (using the available real estate) just below the top title bar. By default, the only search results shown are the pages matching the product / version you're currently viewing. You can expand what is displayed by clicking on the button on the right-hand side of the history bar and choosing the "All" radio option. This will show all recent pages in the history bar for all products / versions.
Within the history config menu you will also see a listing of your recent page visits. The results are filtered by the "Current Product / Version" and "All" radio options. Clicking on the button will clear the history bar as well as the history kept in local storage.
If "All" is selected in the history config menu the checkbox option for "Show product details in the history bar" will be enabled. When checked, the product/version for each historic page will show alongside the page name in the history bar. Hovering the cursor over the page names in the history bar will also show the product/version as a tooltip.
Both API docs and guides can be searched for using the search field at the top of the page.
On API doc pages there is also a filter input field that filters the member rows using the filter string. In addition to filtering by string you can filter the class members by access level, inheritance, and read only. This is done using the checkboxes at the top of the page.
The checkbox at the bottom of the API class navigation tree filters the class list to include or exclude private classes.
Clicking on an empty search field will show your last 10 searches for quick navigation.
Each API doc page (with the exception of Javascript primitives pages) has a menu view of metadata relating to that class. This metadata view will have one or more of the following:
Ext.button.Button class has an alternate class name of Ext.Button). Alternate class
names are commonly maintained for backward compatibility.Runnable examples (Fiddles) are expanded on a page by default. You can collapse and expand example code blocks individually using the arrow on the top-left of the code block. You can also toggle the collapse state of all examples using the toggle button on the top-right of the page. The toggle-all state will be remembered between page loads.
Class members are collapsed on a page by default. You can expand and collapse members using the arrow icon on the left of the member row or globally using the expand / collapse all toggle button top-right.
Viewing the docs on narrower screens or browsers will result in a view optimized for a smaller form factor. The primary differences between the desktop and "mobile" view are:
The class source can be viewed by clicking on the class name at the top of an API doc page. The source for class members can be viewed by clicking on the "view source" link on the right-hand side of the member row.
View Model that holds the "selectedColor" of the color picker container.
This object holds the arbitrary data that populates the ViewModel and is
then available for binding.
Defaults to:
true
Available since: 5.0.0
Sets data directly at the level of this viewmodel. This method does not climb
to set data on parent view models. Passing undefined will clear the value
in this viewmodel, which means that this viewmodel is free to inherit data
from a parent. See "Inheriting Data" in the class introduction for more information.
data : Object
The new data to set.
An object that defines named values whose value is managed by function calls. The names of the properties of this object are assigned as values in the ViewModel.
For example:
formulas: {
xy: function (get) { return get('x') * get('y'); }
}
For more details about defining a formula, see Ext.app.bind.Formula.
Defaults to:
null
Available since: 5.0.0
Links provide a way to assign a simple name to a more complex bind. The primary use for this is to assign names to records in the data model.
links: {
theUser: {
type: 'User',
id: 12
}
}
It is also possible to force a new phantom record to be created by not specifying an
id but passing create: true as part of the descriptor. This is often useful when
creating a new record for a child session.
links: {
newUser: {
type: 'User',
create: true
}
}
create can also be an object containing initial data for the record.
links: {
newUser: {
type: 'User',
create: {
firstName: 'John',
lastName: 'Smith'
}
}
}
While that is the typical use, the value of each property in links may also be
a bind descriptor (see method-bind for the various forms of bind
descriptors).
Defaults to:
null
Available since: 5.0.0
The parent ViewModel of this ViewModel. Once set, this cannot be changed.
Defaults to:
null
Available since: 5.0.0
A reference to the root "stub" (an object that manages bindings).
Defaults to:
true
Available since: 5.0.0
The scheduler used to schedule and manage the delivery of notifications for
all connections to this ViewModel and any other attached to it. The normal
process to initialize the scheduler is to get the scheduler used by the
parent or session and failing either of those, create one.
Defaults to:
null
Available since: 5.0.0
The schema to use for getting information about entities.
Defaults to:
'default'
The session used to manage the data model (records and stores).
Defaults to:
null
Available since: 5.0.0
Gets the session attached to this (or a parent) ViewModel. See the session configuration.
The session. null if no session exists.
A declaration of Ext.data.Store configurations that are first processed as
binds to produce an effective store configuration.
A simple store definition. We can reference this in our bind statements using the
{users} as we would with other data values.
new Ext.app.ViewModel({
stores: {
users: {
model: 'User',
autoLoad: true
}
}
});
This store definition contains a dynamic binding. The store will not be created until the initial value for groupId is set. Once that occurs, the store is created with the appropriate filter configuration. Subsequently, once we change the group value, the old filter will be overwritten with the new value.
var viewModel = new Ext.app.ViewModel({
stores: {
users: {
model: 'User',
filters: [{
property: 'groupId',
value: '{groupId}'
}]
}
}
});
viewModel.set('groupId', 1); // This will trigger the store creation with the filter.
viewModel.set('groupId', 2); // The filter value will be changed.
This store uses Ext.data.ChainedStore to create a store backed by the data in another store. By specifying a string as the store, it will bind our creation and backing to the other store. This functionality is especially useful when wanting to display a different "view" of a store, for example a different sort order or different filters.
var viewModel = new Ext.app.ViewModel({
stores: {
allUsers: {
model: 'User',
autoLoad: true
},
children: {
source: '{allUsers}',
filters: [{
property: 'age',
value: 18,
operator: '<'
}]
}
}
});
Defaults to:
null
Available since: 5.0.0
The Container that owns this ViewModel instance.
Defaults to:
null
Available since: 5.0.0
The value true causes config values to be stored on instances using a
property name prefixed with an underscore ("_") character. A value of false
stores config values as properties using their exact name (no prefix).
Defaults to:
true
Available since: 5.0.0
The value true instructs the initConfig method to only honor values for
properties declared in the config block of a class. When false, properties
that are not declared in a config block will be placed on the instance.
Defaults to:
true
Available since: 5.0.0
A prototype-chained object storing transform method names and priorities stored on the class prototype. On first instantiation, this object is converted into an array that is sorted by priority and stored on the constructor.
Defaults to:
{}
true indicates an id was auto-generated rather than provided by configuration.
Defaults to:
false
Available since: 6.7.0
Setting this property to false will prevent nulling object references
on a Class instance after destruction. Setting this to "async" will delay
the clearing for approx 50ms.
Defaults to:
true
Available since: 6.2.0
Setting this property to true will result in setting the object's
prototype to null after the destruction sequence is fully completed.
After that, most attempts at calling methods on the object instance
will result in "method not defined" exception. This can be very helpful
with tracking down otherwise hard to find bugs like runaway Ajax requests,
timed functions not cleared on destruction, etc.
Note that this option can only work in browsers that support Object.setPrototypeOf
method, and is only available in debugging mode.
Defaults to:
false
Available since: 6.2.0
This object holds all of the properties of this ViewModel. It is
prototype chained to the linkData which is, in turn, prototype chained
to (if present) the data object of the parent ViewModel.
Defaults to:
Ext.Object.chain(linkData)
Available since: 5.0.0
This property is set to true after the destroy method is called.
Defaults to:
false
If this property is specified by the target class of this mixin its properties are
used to configure the created Ext.Factory.
This property is set to true during the call to initConfig.
Defaults to:
false
Available since: 5.0.0
This property is set to true if this instance is the first of its class.
Defaults to:
false
Available since: 5.0.0
This value is true and is used to identify plain objects from instances of
a defined class.
Defaults to:
true
This object is used to hold the result of a linked value. This is done so that the data object hasOwnProperty equates to whether or not this property is owned by this instance or inherited.
Defaults to:
linkData = parent ? Ext.Object.chain(parent.getData()) : {}
Available since: 5.0.0
Get the reference to the current class from which this object was instantiated. Unlike
Ext.Base#statics, this.self is scope-dependent and it's meant to be used
for dynamic inheritance. See Ext.Base#statics for a detailed comparison
Ext.define('My.Cat', {
statics: {
speciesName: 'Cat' // My.Cat.speciesName = 'Cat'
},
constructor: function() {
alert(this.self.speciesName); // dependent on 'this'
},
clone: function() {
return new this.self();
}
});
Ext.define('My.SnowLeopard', {
extend: 'My.Cat',
statics: {
speciesName: 'Snow Leopard' // My.SnowLeopard.speciesName = 'Snow Leopard'
}
});
var cat = new My.Cat(); // alerts 'Cat'
var snowLeopard = new My.SnowLeopard(); // alerts 'Snow Leopard'
var clone = snowLeopard.clone();
alert(Ext.getClassName(clone)); // alerts 'My.SnowLeopard'
Defaults to:
Base
This method applies a versioned, deprecation declaration to this class. This
is typically called by the deprecated config.
deprecations : Object
This method requests that data in this ViewModel be delivered to the specified
callback. The data desired is given in a "bind descriptor" which is the first
argument.
A simple call might look like this:
var binding = vm.bind('{foo}', this.onFoo, this);
binding.destroy(); // when done with the binding
Options for the binding can be provided in the last argument:
var binding = vm.bind('{foo}', this.onFoo, this, {
deep: true
});
Alternatively, bind options can be combined with the bind descriptor using only the first argument:
var binding = vm.bind({
bindTo: '{foo}', // the presence of bindTo identifies this form
deep: true
}, this.onFoo, this);
See the class documentation for more details on Bind Descriptors and options.
descriptor : String/Object/Array
The bind descriptor. See class description for details.
callback : Function
The function to call with the value of the bound property.
scope : Object (optional)
The scope (this pointer) for the callback.
options : Object (optional)
Additional options to configure the
Ext.app.bind.Binding. If this parameter is provided, the bindTo form
of combining options and bind descriptor is not recognized.
The binding.
Call the original method that was previously overridden with Ext.Base#override
Ext.define('My.Cat', {
constructor: function() {
alert("I'm a cat!");
}
});
My.Cat.override({
constructor: function() {
alert("I'm going to be a cat!");
this.callOverridden();
alert("Meeeeoooowwww");
}
});
var kitty = new My.Cat(); // alerts "I'm going to be a cat!"
// alerts "I'm a cat!"
// alerts "Meeeeoooowwww"
args : Array/Arguments
The arguments, either an array or the arguments object
from the current method, for example: this.callOverridden(arguments)
Returns the result of calling the overridden method
Deprecated since version 4.1.0
Use method-callParent instead.
Call the "parent" method of the current method. That is the method previously overridden by derivation or by an override (see Ext#define).
Ext.define('My.Base', {
constructor: function(x) {
this.x = x;
},
statics: {
method: function(x) {
return x;
}
}
});
Ext.define('My.Derived', {
extend: 'My.Base',
constructor: function() {
this.callParent([21]);
}
});
var obj = new My.Derived();
alert(obj.x); // alerts 21
This can be used with an override as follows:
Ext.define('My.DerivedOverride', {
override: 'My.Derived',
constructor: function(x) {
this.callParent([x*2]); // calls original My.Derived constructor
}
});
var obj = new My.Derived();
alert(obj.x); // now alerts 42
This also works with static and private methods.
Ext.define('My.Derived2', {
extend: 'My.Base',
// privates: {
statics: {
method: function(x) {
return this.callParent([x*2]); // calls My.Base.method
}
}
});
alert(My.Base.method(10)); // alerts 10
alert(My.Derived2.method(10)); // alerts 20
Lastly, it also works with overridden static methods.
Ext.define('My.Derived2Override', {
override: 'My.Derived2',
// privates: {
statics: {
method: function(x) {
return this.callParent([x*2]); // calls My.Derived2.method
}
}
});
alert(My.Derived2.method(10); // now alerts 40
To override a method and replace it and also call the superclass method, use method-callSuper. This is often done to patch a method to fix a bug.
args : Array/Arguments
The arguments, either an array or the arguments object
from the current method, for example: this.callParent(arguments)
Returns the result of calling the parent method
This method is used by an override to call the superclass method but bypass any overridden method. This is often done to "patch" a method that contains a bug but for whatever reason cannot be fixed directly.
Consider:
Ext.define('Ext.some.Class', {
method: function() {
console.log('Good');
}
});
Ext.define('Ext.some.DerivedClass', {
extend: 'Ext.some.Class',
method: function() {
console.log('Bad');
// ... logic but with a bug ...
this.callParent();
}
});
To patch the bug in Ext.some.DerivedClass.method, the typical solution is to create an
override:
Ext.define('App.patches.DerivedClass', {
override: 'Ext.some.DerivedClass',
method: function() {
console.log('Fixed');
// ... logic but with bug fixed ...
this.callSuper();
}
});
The patch method cannot use method-callParent to call the superclass
method since that would call the overridden method containing the bug. In
other words, the above patch would only produce "Fixed" then "Good" in the
console log, whereas, using callParent would produce "Fixed" then "Bad"
then "Good".
args : Array/Arguments
The arguments, either an array or the arguments object
from the current method, for example: this.callSuper(arguments)
Returns the result of calling the superclass method
This method is called to cleanup an object and its resources. After calling this method, the object should not be used any further in any way, including access to its methods and properties.
To prevent potential memory leaks, all object references will be nulled
at the end of destruction sequence, unless clearPropertiesOnDestroy
is set to false.
Destroys member properties by name.
If a property name is the name of a config, the getter is not invoked, so if the config has not been initialized, nothing will be done.
The property will be destroyed, and the corrected name (if the property is a config
and config names are prefixed) will set to null in this object's dictionary.
args : String...
One or more names of the properties to destroy and remove from the object.
Get a value from the data for this viewmodel.
path : String
The path of the data to retrieve.
var value = vm.get('theUser.address.city');
The data stored at the passed path.
Returns a specified config property value. If the name parameter is not passed, all current configuration options will be returned as key value pairs.
name : String (optional)
The name of the config property to get.
peek : Boolean (optional)
true to peek at the raw value without calling the getter.
Defaults to: false
ifInitialized : Boolean (optional)
true to only return the initialized property
value, not the raw config value, and not to trigger initialization. Returns
undefined if the property has not yet been initialized.
Defaults to: false
The config property value.
Retrieves the id. This method Will auto-generate an id if one has not already
been configured.
id
Returns the initial configuration passed to the constructor when instantiating this class.
Given this example Ext.button.Button definition and instance:
Ext.define('MyApp.view.Button', {
extend: 'Ext.button.Button',
xtype: 'mybutton',
scale: 'large',
enableToggle: true
});
var btn = Ext.create({
xtype: 'mybutton',
renderTo: Ext.getBody(),
text: 'Test Button'
});
Calling btn.getInitialConfig() would return an object including the config
options passed to the create method:
xtype: 'mybutton',
renderTo: // The document body itself
text: 'Test Button'
Calling btn.getInitialConfig('text')returns 'Test Button'.
name : String (optional)
Name of the config option to return.
The full config object or a single config value
when name parameter specified.
Get a record instance given a reference descriptor. Will ask the session if one exists.
type : String/Ext.Class
The model type.
id : Object
The model id.
The model instance.
Gets a store configured via the stores configuration.
key : String
The name of the store.
The store. null if no store exists.
This method looks up the Stub for a single bind descriptor.
bindDescr : String/Object
The bind descriptor.
The Stub associated to the bind descriptor.
Initialize configuration for this class. a typical example:
Ext.define('My.awesome.Class', {
// The default config
config: {
name: 'Awesome',
isAwesome: true
},
constructor: function(config) {
this.initConfig(config);
}
});
var awesome = new My.awesome.Class({
name: 'Super Awesome'
});
alert(awesome.getName()); // 'Super Awesome'
instanceConfig : Object
this
Adds a "destroyable" object to an internal list of objects that will be destroyed
when this instance is destroyed (via destroy).
name : String
value : Object
The value passed.
Create a link to a reference. See the links configuration.
key : String
The name for the link.
reference : Object
The reference descriptor.
Forces all bindings in this ViewModel hierarchy to evaluate immediately. Use this to do a synchronous flush of all bindings.
Set a value in the data for this viewmodel. This method will climb to set data on a parent view model if appropriate. See "Inheriting Data" in the class introduction for more information.
path : Object/String
The path of the value to set, or an object literal to set at the root of the viewmodel.
value : Object
The data to set at the value. If the value is an object literal, any required paths will be created.
// Set a single property at the root level
viewModel.set('expiry', Ext.Date.add(new Date(), Ext.Date.DAY, 7));
console.log(viewModel.get('expiry'));
// Sets a single property in user.address, does not overwrite any hierarchy.
viewModel.set('user.address.city', 'London');
console.log(viewModel.get('user.address.city'));
// Sets 2 properties of "user". Overwrites any existing hierarchy.
viewModel.set('user', {firstName: 'Foo', lastName: 'Bar'});
console.log(viewModel.get('user.firstName'));
// Sets a single property at the root level. Overwrites any existing hierarchy.
viewModel.set({rootKey: 1});
console.log(viewModel.get('rootKey'));
Sets a single/multiple configuration options.
name : String/Object
The name of the property to set, or a set of key value pairs to set.
value : Object (optional)
The value to set for the name parameter.
this
Get the reference to the class from which this object was instantiated. Note that unlike
Ext.Base#self, this.statics() is scope-independent and it always returns
the class from which it was called, regardless of what this points to during run-time
Ext.define('My.Cat', {
statics: {
totalCreated: 0,
speciesName: 'Cat' // My.Cat.speciesName = 'Cat'
},
constructor: function() {
var statics = this.statics();
// always equals to 'Cat' no matter what 'this' refers to
// equivalent to: My.Cat.speciesName
alert(statics.speciesName);
alert(this.self.speciesName); // dependent on 'this'
statics.totalCreated++;
},
clone: function() {
var cloned = new this.self(); // dependent on 'this'
// equivalent to: My.Cat.speciesName
cloned.groupName = this.statics().speciesName;
return cloned;
}
});
Ext.define('My.SnowLeopard', {
extend: 'My.Cat',
statics: {
speciesName: 'Snow Leopard' // My.SnowLeopard.speciesName = 'Snow Leopard'
},
constructor: function() {
this.callParent();
}
});
var cat = new My.Cat(); // alerts 'Cat', then alerts 'Cat'
var snowLeopard = new My.SnowLeopard(); // alerts 'Cat', then alerts 'Snow Leopard'
var clone = snowLeopard.clone();
alert(Ext.getClassName(clone)); // alerts 'My.SnowLeopard'
alert(clone.groupName); // alerts 'Cat'
alert(My.Cat.totalCreated); // alerts 3
Destroys a given set of linked objects. This is only needed if
the linked object is being destroyed before this instance.
names : String[]
The names of the linked objects to destroy.
this
Watches config properties.
instance.watchConfig({
title: 'onTitleChange',
scope: me
});
Available since: 6.7.0
name : Object
fn : Object
scope : Object
Adds new config properties to this class. This is called for classes when they are declared, then for any mixins that class may define and finally for any overrides defined that target the class.
config : Object
mixinClass : Ext.Class (optional)
The mixin class if the configs are from a mixin.
name : Object
member : Object
privacy : Object
Add methods / properties to the prototype of this class.
Ext.define('My.awesome.Cat', {
constructor: function() {
...
}
});
My.awesome.Cat.addMembers({
meow: function() {
alert('Meowww...');
}
});
var kitty = new My.awesome.Cat();
kitty.meow();
members : Object
The members to add to this class.
isStatic : Boolean (optional)
Pass true if the members are static.
Defaults to: false
privacy : Boolean (optional)
Pass true if the members are private. This
only has meaning in debug mode and only for methods.
Defaults to: false
Add / override static properties of this class.
Ext.define('My.cool.Class', {
...
});
My.cool.Class.addStatics({
someProperty: 'someValue', // My.cool.Class.someProperty = 'someValue'
method1: function() { ... }, // My.cool.Class.method1 = function() { ... };
method2: function() { ... } // My.cool.Class.method2 = function() { ... };
});
members : Object
this
Borrow another class' members to the prototype of this class.
Ext.define('Bank', {
money: '$$$',
printMoney: function() {
alert('$$$$$$$');
}
});
Ext.define('Thief', {
...
});
Thief.borrow(Bank, ['money', 'printMoney']);
var steve = new Thief();
alert(steve.money); // alerts '$$$'
steve.printMoney(); // alerts '$$$$$$$'
fromClass : Ext.Base
The class to borrow members from
members : Array/String
The names of the members to borrow
this
Create a new instance of this Class.
Ext.define('My.cool.Class', {
...
});
My.cool.Class.create({
someConfig: true
});
All parameters are passed to the constructor of the class.
the created instance.
Create aliases for existing prototype methods. Example:
Ext.define('My.cool.Class', {
method1: function() { ... },
method2: function() { ... }
});
var test = new My.cool.Class();
My.cool.Class.createAlias({
method3: 'method1',
method4: 'method2'
});
test.method3(); // test.method1()
My.cool.Class.createAlias('method5', 'method3');
test.method5(); // test.method3() -> test.method1()
alias : String/Object
The new method name, or an object to set multiple aliases. See flexSetter
origin : String/Object
The original method name
Returns the Ext.Configurator for this class.
Get the current class' name in string format.
Ext.define('My.cool.Class', {
constructor: function() {
alert(this.self.getName()); // alerts 'My.cool.Class'
}
});
My.cool.Class.getName(); // 'My.cool.Class'
className
Used internally by the mixins pre-processor
name : Object
mixinClass : Object
Override members of this class. Overridden methods can be invoked via callParent.
Ext.define('My.Cat', {
constructor: function() {
alert("I'm a cat!");
}
});
My.Cat.override({
constructor: function() {
alert("I'm going to be a cat!");
this.callParent(arguments);
alert("Meeeeoooowwww");
}
});
var kitty = new My.Cat(); // alerts "I'm going to be a cat!"
// alerts "I'm a cat!"
// alerts "Meeeeoooowwww"
Direct use of this method should be rare. Use Ext.define instead:
Ext.define('My.CatOverride', {
override: 'My.Cat',
constructor: function() {
alert("I'm going to be a cat!");
this.callParent(arguments);
alert("Meeeeoooowwww");
}
});
The above accomplishes the same result but can be managed by the Ext.Loader which can properly order the override and its target class and the build process can determine whether the override is needed based on the required state of the target class (My.Cat).
members : Object
The properties to add to this class. This should be specified as an object literal containing one or more properties.
this class
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