Add ol.Object.unset() method

Allow deleting a property.

src/ol/object.js

@@ -131,7 +131,7 @@ ol.ObjectAccessor.prototype.transform = function(from, to) {
  * property is observable as well as the object as a whole.
  *
  * Classes that inherit from this have pre-defined properties, to which you can
- * add your own. The pre-defined properties are listed in this documentation as
+ * add your owns. The pre-defined properties are listed in this documentation as
  * 'Observable Properties', and have their own accessors; for example,
  * {@link ol.Map} has a `target` property, accessed with `getTarget()`  and
  * changed with `setTarget()`. Not all properties are however settable. There
@@ -163,6 +163,9 @@ ol.ObjectAccessor.prototype.transform = function(from, to) {
  * details, and see {@link ol.dom.Input} for the specific case of binding an
  * object with an HTML element.
  *
+ * Properties can be deleted by using the unset method. E.g.
+ * object.unset('foo').
+ *
  * @constructor
  * @extends {ol.Observable}
  * @param {Object.<string, *>=} opt_values An object with key-value pairs.
@@ -489,3 +492,17 @@ ol.Object.prototype.unbindAll = function() {
     this.unbind(key);
   }
 };
+
+
+/**
+ * Unsets a property.
+ * @param {string} key Key name.
+ * @api
+ */
+ol.Object.prototype.unset = function(key) {
+  if (key in this.values_) {
+    var oldValue = this.values_[key];
+    delete this.values_[key];
+    this.notify(key, oldValue);
+  }
+};

test/spec/ol/object.test.js

@@ -7,7 +7,7 @@ describe('ol.Object', function() {
     o = new ol.Object();
   });
 
-  describe('get and set', function() {
+  describe('get, set and unset', function() {
 
     describe('get an unset property', function() {
       var v;
@@ -18,7 +18,6 @@ describe('ol.Object', function() {
       it('returns undefined', function() {
         expect(v).to.be(undefined);
       });
-
     });
 
     describe('get a set property', function() {
@@ -32,6 +31,17 @@ describe('ol.Object', function() {
         expect(v).to.eql(1);
       });
     });
+
+    describe('unset a set property', function() {
+      beforeEach(function() {
+        o.set('k', 1);
+      });
+
+      it('returns undefined', function() {
+        var v = o.unset('k');
+        expect(v).to.be(undefined);
+      });
+    });
   });
 
   describe('#get()', function() {