Merge pull request #2423 from magento-tango/MAGETWO-73537

MAGETWO-73537 Browser back button issue (Checkout pages)

Author: dhorytskyi

app/code/Magento/Checkout/view/frontend/web/js/model/step-navigator.js

@@ -182,6 +182,15 @@ define([
             });
         },
 
+        /**
+         * Sets window location hash.
+         *
+         * @param {String} hash
+         */
+        setHash: function (hash) {
+            window.location.hash = hash;
+        },
+
         /**
          * Next step.
          */
@@ -199,7 +208,7 @@ define([
             if (steps().length > activeIndex + 1) {
                 code = steps()[activeIndex + 1].code;
                 steps()[activeIndex + 1].isVisible(true);
-                window.location = window.checkoutConfig.checkoutUrl + '#' + code;
+                this.setHash(code);
                 document.body.scrollTop = document.documentElement.scrollTop = 0;
             }
         }

app/code/Magento/Checkout/view/frontend/web/js/view/progress-bar.js

@@ -26,6 +26,11 @@ define([
         initialize: function () {
             this._super();
             $(window).hashchange(_.bind(stepNavigator.handleHash, stepNavigator));
+
+            if (!window.location.hash) {
+                stepNavigator.setHash(stepNavigator.steps().sort(stepNavigator.sortItems)[0].code);
+            }
+
             stepNavigator.handleHash();
         },