var reference = new pc.AssetReference('textureAsset', this, this.app.assets, {
    load: this.onTextureAssetLoad,
    add: this.onTextureAssetAdd,
    remove: this.onTextureAssetRemove
}, this);
reference.id = this.textureAsset.id;

AssetReference(propertyName, parent, registry, callbacks, [scope]) 

An object that manages the case where an object holds a reference to an asset and needs to be notified when changes occur in the asset. e.g. notifications include load, add and remove events.

var reference = new pc.AssetReference('textureAsset', this, this.app.assets, {
    load: this.onTextureAssetLoad,
    add: this.onTextureAssetAdd,
    remove: this.onTextureAssetRemove
}, this);
reference.id = this.textureAsset.id;

Parameters

propertyName	string	The name of the property that the asset is stored under, passed into callbacks to enable updating.
parent	pc.Asset, object	The parent object that contains the asset reference, passed into callbacks to enable updating. Currently an asset, but could be component or other.
registry	pc.AssetRegistry	The asset registry that stores all assets.
callbacks	object	A set of functions called when the asset state changes: load, add, remove.
callbacks.load	object	The function called when the asset loads load(propertyName, parent, asset).
callbacks.add	object	The function called when the asset is added to the registry add(propertyName, parent, asset).
callbacks.remove	object	The function called when the asset is remove from the registry remove(propertyName, parent, asset).
scope	object	The scope to call the callbacks in

numberid 

Get or set the asset id which this references. One of either id or url must be set to initialize an asset reference.

stringurl 

Get or set the asset url which this references. One of either id or url must be called to initialize an asset reference.