background - introduce ObservableStore

1 files changed, 33 insertions, 0 deletions

diff --git a/app/scripts/lib/observable/index.js b/app/scripts/lib/observable/index.js
new file mode 100644
index 000000000..d193e5554
--- /dev/null
+++ b/app/scripts/lib/observable/index.js
@@ -0,0 +1,33 @@
+const EventEmitter = require('events').EventEmitter
+
+class ObservableStore extends EventEmitter {
+
+  constructor (initialState) {
+    super()
+    this._state = initialState
+  }
+
+  get () {
+    return this._state
+  }
+
+  put (newState) {
+    this._put(newState)
+  }
+
+  subscribe (handler) {
+    this.on('update', handler)
+  }
+
+  unsubscribe (handler) {
+    this.removeListener('update', handler)
+  }
+
+  _put (newState) {
+    this._state = newState
+    this.emit('update', newState)
+  }
+
+}
+
+module.exports = ObservableStore