attributeChangedCallback(attrName, oldValue, newValue) {
		if (oldValue === newValue) { return; }
		const { attr2prop = identity } = this.constructor.classProperties.get(attrName) || defaultPropertyDeclaration;
		this[attrName] = attr2prop.call(this, newValue);
	}
/**
	 * Called when an observed attribute has been added, removed, updated, or replaced.
	 * Also called for initial values when an element is created by the parser, or upgraded.
	 * Note: only attributes listed in the observedAttributes property will receive this callback.
	 *
	 * @param {string} attrName attribute name
	 * @param {(string | null)} oldValue old value of the attribute
	 * @param {(string | null)} newValue new value of the attribute
	 * @memberof BaseElement
	 */
Called when an observed attribute has been added, removed, updated, or replaced.
Also called for initial values when an element is created by the parser, or upgraded.
Note: only attributes listed in the observedAttributes property will receive this callback.

@param {string} attrName attribute name
@param {(string | null)} oldValue old value of the attribute
@param {(string | null)} newValue new value of the attribute
@memberof BaseElement
Called when an observed attribute has been added removed updated or replaced . Also called for initial values when an element is created by the parser or upgraded . Note : only attributes listed in the observedAttributes property will receive this callback . @param { string } attrName attribute name @param { ( string | null ) } oldValue old value of the attribute @param { ( string | null ) } newValue new value of the attribute @memberof BaseElement
attributeChangedCallback(attrName, oldValue, newValue) {
		if (oldValue === newValue) { return; }
		const { attr2prop = identity } = this.constructor.classProperties.get(attrName) || defaultPropertyDeclaration;
		this[attrName] = attr2prop.call(this, newValue);
	}
attributeChangedCallback ( attrName , oldValue , newValue ) { if ( oldValue === newValue ) { return ; } const { attr2prop = identity } = this . constructor . classProperties . get ( attrName ) || defaultPropertyDeclaration ; this [ attrName ] = attr2prop . call ( this , newValue ) ; }
Called when an observed attribute has been added, removed, updated, or replaced.
Called when an observed attribute has been added removed updated or replaced .