0.2.2

view/frontend/web/main.js

@@ -20,16 +20,41 @@ define([
 	*/
 	initialize: function() {
 		this._super();
+		/** @type {?Object} */
+		var prevAddress;
 		quote.billingAddress.subscribe(
 			/**
 			 * 2017-04-04
 			 * newAddress is null if a customer has just unchecked
 			 * the «My billing and shipping address are the same» checkbox,
 			 * but does not select another address yet.
+			 * @used-by Magento_Checkout/js/action/select-billing-address:
+			 * 		quote.billingAddress(address);
+			 * https://github.com/magento/magento2/blob/2.1.5/app/code/Magento/Checkout/view/frontend/web/js/action/select-billing-address.js#L23
 			 * @param {?Object} newAddress
 			 */
 			function(newAddress) {
-				debugger;
+				/**
+				 * 2017-04-04
+				 * Note #1
+				 * Naive newAddress !== prevAddress does not work correctly.
+				 * @uses Magento_Customer/js/model/customer/address::getKey()
+				 *	getKey: function() {
+				 *		return this.getType() + this.customerAddressId;
+				 *	}
+				 * https://github.com/magento/magento2/blob/2.1.5/app/code/Magento/Customer/view/frontend/web/js/model/customer/address.js#L48-L50
+				 * It returns a string like «customer-address4».
+				 * Note #2
+				 * !newAddress ^ !prevAddress is for situations
+				 * when newAddress or prevAddress is null or prevAddress is undefined:
+				 * http://stackoverflow.com/a/4540443
+				 */
+				if (!newAddress ^ !prevAddress || newAddress.getKey() !== prevAddress.getKey()) {
+					prevAddress = newAddress;
+					if (newAddress) {
+						console.log(newAddress);
+					}
+				}
 			}
 		);
 		return this;