Implement back/forward buttons (fix #180)

renderer/lib/location-history.js

@@ -0,0 +1,61 @@
+module.exports = LocationHistory
+
+function LocationHistory () {
+  if (!new.target) return new LocationHistory()
+  this._history = []
+  this._forward = []
+}
+
+LocationHistory.prototype.go = function (page) {
+  console.log('go', page)
+  this.clearForward()
+  this._go(page)
+}
+
+LocationHistory.prototype._go = function (page) {
+  if (page.onbeforeload) {
+    page.onbeforeload((err) => {
+      if (err) return
+      this._history.push(page)
+    })
+  } else {
+    this._history.push(page)
+  }
+}
+
+LocationHistory.prototype.back = function () {
+  if (this._history.length <= 1) return
+
+  var page = this._history.pop()
+
+  if (page.onbeforeunload) {
+    page.onbeforeunload(() => {
+      this._forward.push(page)
+    })
+  } else {
+    this._forward.push(page)
+  }
+}
+
+LocationHistory.prototype.forward = function () {
+  if (this._forward.length === 0) return
+
+  var page = this._forward.pop()
+  this._go(page)
+}
+
+LocationHistory.prototype.clearForward = function () {
+  this._forward = []
+}
+
+LocationHistory.prototype.current = function () {
+  return this._history[this._history.length - 1]
+}
+
+LocationHistory.prototype.hasBack = function () {
+  return this._history.length > 1
+}
+
+LocationHistory.prototype.hasForward = function () {
+  return this._forward.length > 0
+}