support history navigation

src/background/key-queue.js

@@ -15,6 +15,8 @@ const DEFAULT_KEYMAP = [
   { keys: [{ code: KeyboardEvent.DOM_VK_L }], action: [ actions.TABS_NEXT, 1 ]},
   { keys: [{ code: KeyboardEvent.DOM_VK_F }], action: [ actions.FOLLOW_START, false ]},
   { keys: [{ code: KeyboardEvent.DOM_VK_F, shift: true }], action: [ actions.FOLLOW_START, true ]},
+  { keys: [{ code: KeyboardEvent.DOM_VK_H, shift: true }], action: [ actions.HISTORY_PREV ]},
+  { keys: [{ code: KeyboardEvent.DOM_VK_L, shift: true }], action: [ actions.HISTORY_NEXT ]},
 ]
 
 export default class KeyQueue {

src/content/histories.js

@@ -0,0 +1,8 @@
+const prev = (win) => {
+  win.history.back()
+};
+const next = (win) => {
+  win.history.forward()
+};
+
+export { prev, next };

src/content/index.js

@@ -1,7 +1,8 @@
 import * as scrolls from './scrolls';
+import * as histories from './histories';
+import * as actions from '../shared/actions';
 import FooterLine from './footer-line';
 import Follow from './follow';
-import * as actions from '../shared/actions';
 
 var footer = null;
 
@@ -56,6 +57,12 @@ const invokeEvent = (action) => {
   case actions.FOLLOW_START:
     new Follow(window.document, action[1] || false);
     break;
+  case actions.HISTORY_PREV:
+    histories.prev(window);
+    break;
+  case actions.HISTORY_NEXT:
+    histories.next(window);
+    break;
   }
 }
 

src/shared/actions.js

@@ -9,6 +9,8 @@ export const SCROLL_DOWN = 'scroll.down';
 export const SCROLL_TOP = 'scroll.top';
 export const SCROLL_BOTTOM = 'scroll.bottom';
 export const FOLLOW_START = 'follow.start';
+export const HISTORY_PREV = 'history.prev';
+export const HISTORY_NEXT = 'history.next';
 
 const BACKGROUND_ACTION_SET = new Set([
   TABS_CLOSE,
@@ -24,7 +26,9 @@ const CONTENT_ACTION_SET = new Set([
   SCROLL_DOWN,
   SCROLL_TOP,
   SCROLL_BOTTOM,
-  FOLLOW_START
+  FOLLOW_START,
+  HISTORY_PREV,
+  HISTORY_NEXT
 ]);
 
 export const isBackgroundAction = (action) => {