Attribute provides configurable attribute support along with attribute change events. It is designed to be augmented on to a host class, and provides the host with the ability to configure attributes to store and retrieve state, along with attribute change events.
For example, attributes added to the host can be configured:
See the addAttr method, for the complete set of configuration options available for attributes.
NOTE: Most implementations will be better off extending the Base class, instead of augmenting Attribute directly. Base augments Attribute and will handle the initial configuration of attributes for derived classes, accounting for values passed into the constructor.
_addAttrscfgs
values
lazy
Implementation behind the public addAttrs method.
This method is invoked directly by get if it encounters a scenario in which an attribute's valueFn attempts to obtain the value an attribute in the same group of attributes, which has not yet been added (on demand initialization).
cfgs
Object
An object with attribute name/configuration pairs.
values
Object
An object with attribute name/value pairs, defining the initial values to apply. Values defined in the cfgs argument will be over-written by values in this argument unless defined as read only.
lazy
Boolean
Whether or not to delay the intialization of these attributes until the first call to get/set. Individual attributes can over-ride this behavior by defining a lazyAdd configuration property in their configuration. See addAttr.
_addLazyAttrname
[lazyCfg]
Finishes initializing an attribute which has been lazily added.
_addOutOfOrdername
cfg
Utility method used by get/set to add attributes encountered out of order when calling addAttrs().
For example, if:
this.addAttrs({
foo: {
setter: function() {
// make sure this bar is available when foo is added
this.get("bar");
}
},
bar: {
value: ...
}
});_defAttrChangeFne
eventFastPath
Default function for attribute change events.
e
EventFacade
The event object for attribute change events.
eventFastPath
Boolean
Whether or not we're using this as a fast path in the case of no listeners or not
_fireAttrChangeattrName
subAttrName
currVal
newVal
opts
[cfg]
Utility method to help setup the event payload and fire the attribute change event.
attrName
String
The name of the attribute
subAttrName
String
The full path of the property being changed, if this is a sub-attribute value being change. Otherwise null.
currVal
Any
The current value of the attribute
newVal
Any
The new value of the attribute
opts
Object
Any additional event data to mix into the attribute change event's event facade.
[cfg]
Object
optional
The attribute config stored in State, if already available.
_getAttrname
Provides the common implementation for the public get method, allowing Attribute hosts to over-ride either method.
See get for argument details.
name
String
The name of the attribute.
The value of the attribute.
_getAttrCfgname
Returns an object with the configuration properties (and value) for the given attribute. If attrName is not provided, returns the configuration properties for all attributes.
name
String
Optional. The attribute name. If not provided, the method will return the configuration for all attributes.
The configuration properties for the given attribute, or all attributes.
_getAttrInitValattr
cfg
initValues
Returns the initial value of the given attribute from either the default configuration provided, or the over-ridden value if it exists in the set of initValues provided and the attribute is not read-only.
The initial value of the attribute.
_getAttrsattrs
Implementation behind the public getAttrs method, to get multiple attribute values.
An object with attribute name/value pairs.
_getFullTypetype
Returns the fully qualified type, given a short type string. That is, returns "foo:bar" when given "bar" if "foo" is the configured prefix.
NOTE: This method, unlike _getType, does no checking of the value passed in, and is designed to be used with the low level _publish() method, for critical path implementations which need to fast-track publish for performance reasons.
type
String
The short type to prefix
The prefixed type, if a prefix is set, otherwise the type passed in
_getStateValname
[cfg]
Gets the stored value for the attribute, from either the internal state object, or the state proxy if it exits
The stored value of the attribute
_getTypeIf the instance has a prefix attribute and the event type is not prefixed, the instance prefix is applied to the supplied type.
_hasPotentialSubscribersfullType
fullType
String
The fully prefixed type name
Whether the event has potential subscribers or not
_initAttrHostattrs
values
lazy
Constructor logic for attributes. Initializes the host state, and sets up the inital attributes passed to the constructor.
attrs
Object
The attributes to add during construction (passed through to addAttrs). These can also be defined on the constructor being augmented with Attribute by defining the ATTRS property on the constructor.
values
Object
The initial attribute values to apply (passed through to addAttrs). These are not merged/cloned. The caller is responsible for isolating user provided values if required.
lazy
Boolean
Whether or not to add attributes lazily (passed through to addAttrs).
_initAttrsattrs
values
lazy
Utility method to set up initial attributes defined during construction, either through the constructor.ATTRS property, or explicitly passed in.
attrs
Object
The attributes to add during construction (passed through to addAttrs). These can also be defined on the constructor being augmented with Attribute by defining the ATTRS property on the constructor.
values
Object
The initial attribute values to apply (passed through to addAttrs). These are not merged/cloned. The caller is responsible for isolating user provided values if required.
lazy
Boolean
Whether or not to add attributes lazily (passed through to addAttrs).
_isLazyAttrname
Checks whether or not the attribute is one which has been added lazily and still requires initialization.
name
String
The name of the attribute
true if it's a lazily added attribute, false otherwise.
_monitorwhat
eventType
o
This is the entry point for the event monitoring system. You can monitor 'attach', 'detach', 'fire', and 'publish'. When configured, these events generate an event. click -> click_attach, click_detach, click_publish -- these can be subscribed to like other events to monitor the event system. Inividual published events can have monitoring turned on or off (publish can't be turned off before it it published) by setting the events 'monitor' config.
what
String
'attach', 'detach', 'fire', or 'publish'
eventType
String | CustomEvent
The prefixed name of the event being monitored, or the CustomEvent object.
o
Object
Information about the event interaction, such as fire() args, subscription category, publish config
_normAttrValsvalueHash
Utility method to split out simple attribute name/value pairs ("x") from complex attribute name/value pairs ("x.y.z"), so that complex attributes can be keyed by the top level attribute name.
valueHash
Object
An object with attribute name/value pairs
An object literal with 2 properties - "simple" and "complex", containing simple and complex attribute values respectively keyed by the top level attribute name, or null, if valueHash is falsey.
_parseTypeReturns an array with the detach key (if provided), and the prefixed event name from _getType Y.on('detachcategory| menu:click', fn)
_protectAttrsattrs
Utility method to protect an attribute configuration hash, by merging the entire object and the individual attr config objects.
attrs
Object
A hash of attribute to configuration object pairs.
A protected version of the attrs argument.
_publishfullType
etOpts
ceOpts
The low level event publish implementation. It expects all the massaging to have been done
outside of this method. e.g. the type to fullType conversion. It's designed to be a fast
path publish, which can be used by critical code paths to improve performance.
The published event. If called without etOpts or ceOpts, this will
be the default CustomEvent instance, and can be configured independently.
_setname
val
[opts]
Allows setting of readOnly/writeOnce attributes. See set for argument details.
A reference to the host object.
_setAttrname
value
[opts]
force
Provides the common implementation for the public set and protected _set methods.
See set for argument details.
A reference to the host object.
_setAttrsattrs
[opts]
Implementation behind the public setAttrs method, to set multiple attribute values.
A reference to the host object.
_setAttrValattrName
subAttrName
prevVal
newVal
[opts]
[attrCfg]
Updates the stored value of the attribute in the privately held State object, if validation and setter passes.
attrName
String
The attribute name.
subAttrName
String
The sub-attribute name, if setting a sub-attribute property ("x.y.z").
prevVal
Any
The currently stored value of the attribute.
newVal
Any
The value which is going to be stored.
[opts]
Object
optional
Optional data providing the circumstances for the change.
[attrCfg]
Object
optional
Optional config hash for the attribute. This is added for performance along the critical path, where the calling method has already obtained the config from state.
true if the new attribute value was stored, false if not.
_setStateValname
value
Sets the stored value for the attribute, in either the internal state object, or the state proxy if it exits
name
String
The name of the attribute
value
Any
The value of the attribute
addAttrname
config
lazy
Adds an attribute with the provided configuration to the host object.
The config argument object supports the following properties:
A function, which will return the initial value to set on the attribute. This is useful for cases where the attribute configuration is defined statically, but needs to reference the host instance ("this") to obtain an initial value. If both the value and valueFn properties are defined, the value returned by the valueFn has precedence over the value property, unless it returns undefined, in which case the value property is used.
valueFn can also be set to a string, representing the name of the instance method to be used to retrieve the value.
The writeOnce attribute can also be set to the string "initOnly", in which case the attribute can only be set during initialization (when used with Base, this means it can only be set during construction)
The setter function used to massage or normalize the value passed to the set method for the attribute. The value returned by the setter will be the final stored value. Returning Attribute.INVALID_VALUE, from the setter will prevent the value from being stored.
setter can also be set to a string, representing the name of the instance method to be used as the setter function.
The getter function used to massage or normalize the value returned by the get method for the attribute. The value returned by the getter function is the value which will be returned to the user when they invoke get.
getter can also be set to a string, representing the name of the instance method to be used as the getter function.
The validator function invoked prior to setting the stored value. Returning false from the validator function will prevent the value from being stored.
validator can also be set to a string, representing the name of the instance method to be used as the validator function.
The setter, getter and validator are invoked with the value and name passed in as the first and second arguments, and with the context ("this") set to the host object.
Configuration properties outside of the list mentioned above are considered private properties used internally by attribute, and are not intended for public use.
name
String
The name of the attribute.
config
Object
An object with attribute configuration property/value pairs, specifying the configuration for the attribute.
NOTE: The configuration object is modified when adding an attribute, so if you need to protect the original values, you will need to merge the object.
lazy
Boolean
(optional) Whether or not to add this attribute lazily (on the first call to get/set).
A reference to the host object.
addAttrscfgs
values
lazy
Configures a group of attributes, and sets initial values.
NOTE: This method does not isolate the configuration object by merging/cloning. The caller is responsible for merging/cloning the configuration object if required.
cfgs
Object
An object with attribute name/configuration pairs.
values
Object
An object with attribute name/value pairs, defining the initial values to apply. Values defined in the cfgs argument will be over-written by values in this argument unless defined as read only.
lazy
Boolean
Whether or not to delay the intialization of these attributes until the first call to get/set. Individual attributes can over-ride this behavior by defining a lazyAdd configuration property in their configuration. See addAttr.
A reference to the host object.
addTargeto
Registers another EventTarget as a bubble target. Bubble order is determined by the order registered. Multiple targets can be specified.
Events can only bubble if emitFacade is true.
Included in the event-custom-complex submodule.
o
EventTarget
the target to add
aftertype
fn
[context]
[arg*]
Subscribe to a custom event hosted by this object. The supplied callback will execute after any listeners add via the subscribe method, and after the default function, if configured for the event, has executed.
A subscription handle capable of detaching the subscription
attrAddedname
Checks if the given attribute has been added to the host
name
String
The name of the attribute to check.
true if an attribute with the given name has been added, false if it hasn't. This method will return true for lazily added attributes.
beforeExecutes the callback before a DOM event, custom event or method. If the first argument is a function, it is assumed the target is a method. For DOM and custom events, this is an alias for Y.on.
For DOM and custom events: type, callback, context, 0-n arguments
For methods: callback, object (method host), methodName, context, 0-n arguments
detach handle
bubbleevt
Propagate an event. Requires the event-custom-complex module.
evt
CustomEvent
the custom event to propagate
the aggregated return value from Event.Custom.fire
detachtype
fn
context
Detach one or more listeners the from the specified event
type
String | Object
Either the handle to the subscriber or the type of event. If the type is not specified, it will attempt to remove the listener from all hosted events.
fn
Function
The subscribed function to unsubscribe, if not supplied, all subscribers will be removed.
context
Object
The custom object passed to subscribe. This is optional, but if supplied will be used to disambiguate multiple listeners that are the same (e.g., you subscribe many object using a function that lives on the prototype)
the host
detachAlltype
Removes all listeners from the specified event. If the event type is not specified, all listeners from all hosted custom events will be removed.
type
String
The type, or name of the event
firetype
arguments
Fire a custom event by name. The callback functions will be executed from the context specified when the event was created, and with the following parameters.
The first argument is the event type, and any additional arguments are passed to the listeners as parameters. If the first of these is an object literal, and the event is configured to emit an event facade, that object is mixed into the event facade and the facade is provided in place of the original object.
If the custom event object hasn't been created, then the event hasn't been published and it has no subscribers. For performance sake, we immediate exit in this case. This means the event won't bubble, so if the intention is that a bubble target be notified, the event must be published on this object first.
type
String | Object
The type of the event, or an object that contains a 'type' property.
arguments
Object*
an arbitrary set of parameters to pass to the handler. If the first of these is an object literal and the event is configured to emit an event facade, the event facade will replace that parameter after the properties the object literal contains are copied to the event facade.
True if the whole lifecycle of the event went through, false if at any point the event propagation was halted.
getname
Returns the current value of the attribute. If the attribute has been configured with a 'getter' function, this method will delegate to the 'getter' to obtain the value of the attribute.
name
String
The name of the attribute. If the value of the attribute is an Object,
dot notation can be used to obtain the value of a property of the object (e.g. get("x.y.z"))
The value of the attribute
getAttrsattrs
Gets multiple attribute values.
An object with attribute name/value pairs.
getEventtype
prefixed
Returns the custom event of the provided type has been created, a falsy value otherwise
the custom event or null
getTargetsReturns an array of bubble targets for this object.
EventTarget[]
modifyAttrname
config
Updates the configuration of an attribute which has already been added.
The properties which can be modified through this interface are limited to the following subset of attributes, which can be safely modified after a value has already been set on the attribute:
Note: New attributes cannot be added using this interface. New attributes must be added using addAttr, or an appropriate manner for a class which utilises Attributes (e.g. the ATTRS property in Base).
ontype
fn
[context]
[arg*]
Subscribe a callback function to a custom event fired by this object or from an object that bubbles its events to this object.
this.on("change", this._onChange, this);Callback functions for events published with emitFacade = true will
receive an EventFacade as the first argument (typically named "e").
These callbacks can then call e.preventDefault() to disable the
behavior published to that event's defaultFn. See the EventFacade
API for all available properties and methods. Subscribers to
non-emitFacade events will receive the arguments passed to fire()
after the event name.
To subscribe to multiple events at once, pass an object as the first argument, where the key:value pairs correspond to the eventName:callback.
this.on({
"attrChange" : this._onAttrChange,
"change" : this._onChange
});You can also pass an array of event names as the first argument to subscribe to all listed events with the same callback.
this.on([ "change", "attrChange" ], this._onChange);Returning false from a callback is supported as an alternative to
calling e.preventDefault(); e.stopPropagation();. However, it is
recommended to use the event methods whenever possible.
A subscription handle capable of detaching that subscription
oncetype
fn
[context]
[arg*]
Listen to a custom event hosted by this object one time.
This is the equivalent to on except the
listener is immediatelly detached when it is executed.
A subscription handle capable of detaching the subscription
onceAftertype
fn
[context]
[arg*]
Listen to a custom event hosted by this object one time.
This is the equivalent to after except the
listener is immediatelly detached when it is executed.
A subscription handle capable of detaching that subscription
parseTypetype
[pre]
Takes the type parameter passed to 'on' and parses out the various pieces that could be included in the type. If the event type is passed without a prefix, it will be expanded to include the prefix one is supplied or the event target is configured with a default prefix.
an array containing:
protectAttrsattrs
Utility method to protect an attribute configuration hash, by merging the entire object and the individual attr config objects.
attrs
Object
A hash of attribute to configuration object pairs.
A protected version of the attrs argument.
publishtype
opts
Creates a new custom event of the specified type. If a custom event by that name already exists, it will not be re-created. In either case the custom event is returned.
type
String
the type, or name of the event
opts
Object
optional config params. Valid properties are:
[broadcast=false]
Boolean
optional
whether or not the YUI instance and YUI global are notified when the event is fired.
[bubbles=true]
Boolean
optional
Whether or not this event bubbles. Events can
only bubble if emitFacade is true.
[context=this]
Object
optional
the default execution context for the listeners.
[defaultFn]
Function
optional
the default function to execute when this event fires if preventDefault was not called.
[emitFacade=false]
Boolean
optional
whether or not this event emits a facade.
[prefix]
String
optional
the prefix for this targets events, e.g., 'menu' in 'menu:click'.
[fireOnce=false]
Boolean
optional
if an event is configured to fire once, new subscribers after the fire will be notified immediately.
[async=false]
Boolean
optional
fireOnce event listeners will fire synchronously
if the event has already fired unless async is true.
[preventable=true]
Boolean
optional
whether or not preventDefault() has an effect.
[preventedFn]
Function
optional
a function that is executed when preventDefault() is called.
[queuable=false]
Boolean
optional
whether or not this event can be queued during bubbling.
[silent]
Boolean
optional
if silent is true, debug messages are not provided for this event.
[stoppedFn]
Function
optional
a function that is executed when stopPropagation is called.
[monitored]
Boolean
optional
specifies whether or not this event should send notifications about when the event has been attached, detached, or published.
[type]
String
optional
the event type (valid option if not provided as the first parameter to publish).
the custom event
removeAttrname
Removes an attribute from the host object
name
String
The name of the attribute to be removed.
resetname
Resets the attribute (or all attributes) to its initial value, as long as the attribute is not readOnly, or writeOnce.
name
String
Optional. The name of the attribute to reset. If omitted, all attributes are reset.
A reference to the host object.
setname
value
[opts]
Sets the value of an attribute.
name
String
The name of the attribute. If the
current value of the attribute is an Object, dot notation can be used
to set the value of a property within the object (e.g. set("x.y.z", 5)).
value
Any
The value to set the attribute to.
[opts]
Object
optional
Optional data providing the circumstances for the change.
A reference to the host object.
setAttrsattrs
[opts]
Sets multiple attribute values.
A reference to the host object.
subscribesubscribe to an event
unsubscribedetach a listener
unsubscribeAlltype
Removes all listeners from the specified event. If the event type is not specified, all listeners from all hosted custom events will be removed.
type
String
The type, or name of the event
_ATTR_CFGThe list of properties which can be configured for each attribute (e.g. setter, getter, writeOnce etc.).
This property is used internally as a whitelist for faster Y.mix operations.
INVALID_VALUEThe value to return from an attribute setter in order to prevent the set from going through.
You can return this value from your setter if you wish to combine validator and setter functionality into a single setter function, which either returns the massaged value to be stored or AttributeCore.INVALID_VALUE to prevent invalid values from being stored.