Merge pull request #5 from hypothesis/zen-observable-update

zen-observable update

h/static/scripts/annotator/selections.js

@@ -50,7 +50,7 @@ function selections(document) {
     observable.buffer(100, selectionEvents),
 
     // Emit an initial event on the next tick
-    observable.Observable.of({}),
+    observable.delay(0, observable.Observable.of({})),
   ]);
 
   return events.map(function () {

h/static/scripts/util/observable.js

@@ -32,6 +32,28 @@ var Observable = require('zen-observable');
    });
  }
 
+/**
+ * Delay events from a source Observable by `delay` ms.
+ */
+function delay(delay, src) {
+  return new Observable(function (obs) {
+    var timeouts = [];
+    var sub = src.subscribe({
+      next: function (value) {
+        var t = setTimeout(function () {
+          timeouts = timeouts.filter(function (other) { return other !== t; });
+          obs.next(value);
+        }, delay);
+        timeouts.push(t);
+      },
+    });
+    return function () {
+      timeouts.forEach(clearTimeout);
+      sub.unsubscribe();
+    };
+  });
+}
+
  /**
   * Buffers events from a source Observable, waiting for a pause of `delay`
   * ms with no events before emitting the last value from `src`.
@@ -99,6 +121,7 @@ function drop(src, n) {
 
 module.exports = {
   buffer: buffer,
+  delay: delay,
   drop: drop,
   listen: listen,
   merge: merge,

h/static/scripts/util/test/observable-test.js

+'use strict';
+
+var observable = require('../observable');
+
+describe('observable', function () {
+  describe('delay()', function () {
+    var clock;
+
+    beforeEach(function () {
+      clock = sinon.useFakeTimers();
+    });
+
+    afterEach(function () {
+      clock.restore();
+    });
+
+    it('defers events', function () {
+      var received = [];
+      var obs = observable.delay(50, observable.Observable.of('foo'));
+      obs.forEach(function (v) {
+        received.push(v);
+      });
+      assert.deepEqual(received, []);
+      clock.tick(100);
+      assert.deepEqual(received, ['foo']);
+    });
+
+    it('delivers events in sequence', function () {
+      var received = [];
+      var obs = observable.delay(10, observable.Observable.of(1,2));
+      obs.forEach(function (v) {
+        received.push(v);
+      });
+      clock.tick(20);
+      assert.deepEqual(received, [1,2]);
+    });
+  });
+});

package.json

@@ -92,7 +92,7 @@
     "watchify": "^3.7.0",
     "websocket": "^1.0.22",
     "whatwg-fetch": "^0.10.1",
-    "zen-observable": "^0.2.1"
+    "zen-observable": "^0.3.0"
   },
   "browserify": {
     "transform": [