Implemented a method `clear([what])`, to clear items, groups, and configuration of a Timeline instance.

HISTORY.md

@@ -7,6 +7,8 @@ http://visjs.org
 ### Timeline
 
 - Implemented option `minHeight`, similar to option `maxHeight`.
+- Implemented a method `clear([what])`, to clear items, groups, and configuration
+  of a Timeline instance.
 - Added function `repaint()` to force a repaint of the Timeline.
 - Some tweaks in snapping dragged items to nice dates.
 - Made the instance of moment.js packaged with vis.js accessibly via `vis.moment`.
@@ -14,6 +16,7 @@ http://visjs.org
   is `"range"` or `"rangeoverflow"`.
 - Fixed a bug in replacing the DataSet of groups via `Timeline.setGroups(groups)`.
 - Fixed a bug when rendering the Timeline inside a hidden container. 
+- Fixed axis scale being determined wrongly for a second Timeline in a single page.
 
 ### Graph
 
@@ -32,9 +35,9 @@ http://visjs.org
 ### Graph
 
 - Added coordinate conversion from DOM to Canvas.
-- fixed bug where the graph stopped animation after settling in playing with physics.
-- fixed bug where hierarchical physics properties were not handled.
-- added events for change of view and zooming.
+- Fixed bug where the graph stopped animation after settling in playing with physics.
+- Fixed bug where hierarchical physics properties were not handled.
+- Added events for change of view and zooming.
 
 
 ## 2014-05-02, version 1.0.0
@@ -64,8 +67,8 @@ http://visjs.org
 
 ### Graph
 
-- added recalculate hierarchical layout to update node event.
-- added arrowScaleFactor to scale the arrows on the edges.
+- Added recalculate hierarchical layout to update node event.
+- Added arrowScaleFactor to scale the arrows on the edges.
 
 ### DataSet
 
@@ -77,48 +80,53 @@ http://visjs.org
 
 ### Graph
 
-- fixed IE9 bug.
-- style fixes.
-- minor bug fixes.
+- Fixed IE9 bug.
+- Style fixes.
+- Minor bug fixes.
 
 
 ## 2014-04-16, version 0.7.3
 
 ### Graph
 
-- fixed color bug.
-- added pull requests from kannonboy and vierja: tooltip styling, label fill color
+- Fixed color bug.
+- Added pull requests from kannonboy and vierja: tooltip styling, label fill 
+  color.
 
 
 ## 2014-04-09, version 0.7.2
 
 ### Graph
 
-- fixed edge select bug.
-- fixed zoom bug on empty initialization.
+- Fixed edge select bug.
+- Fixed zoom bug on empty initialization.
 
 
 ## 2014-03-27, version 0.7.1
 
 ### Graph
 
-- fixed edge color bug.
-- fixed select event bug.
-- clarified docs, stressing importance of css inclusion for correct display of navigation an manipulation icons.
-- improved and expanded playing with physics (configurePhysics option).
-- added highlights to navigation icons if the corresponding key is pressed.
-- added freezeForStabilization option to improve stabilization with cached positions.
+- Fixed edge color bug.
+- Fixed select event bug.
+- Clarified docs, stressing importance of css inclusion for correct display of 
+  navigation an manipulation icons.
+- Improved and expanded playing with physics (configurePhysics option).
+- Added highlights to navigation icons if the corresponding key is pressed.
+- Added freezeForStabilization option to improve stabilization with cached 
+  positions.
 
 
 ## 2014-03-07, version 0.7.0
 
 ### Graph
 
-- changed navigation CSS. Icons are now always correctly positioned.
-- added stabilizationIterations option to graph.
-- added storePosition() method to save the XY positions of nodes in the DataSet.
-- separated allowedToMove into allowedToMoveX and allowedToMoveY. This is required for initializing nodes from hierarchical layouts after storePosition().
-- added color options for the edges.
+- Changed navigation CSS. Icons are now always correctly positioned.
+- Added stabilizationIterations option to graph.
+- Added storePosition() method to save the XY positions of nodes in the DataSet.
+- Separated allowedToMove into allowedToMoveX and allowedToMoveY. This is 
+  required for initializing nodes from hierarchical layouts after 
+  storePosition().
+- Added color options for the edges.
 
 
 ## 2014-03-06, version 0.6.1
@@ -132,7 +140,8 @@ http://visjs.org
 
 ### Timeline
 
-- Fixed a bug with options `margin.axis` and `margin.item` being ignored when setting them to zero.
+- Fixed a bug with options `margin.axis` and `margin.item` being ignored when 
+  setting them to zero.
 - Some clarifications in the documentation.
 
 
@@ -140,7 +149,8 @@ http://visjs.org
 
 ### Graph
 
-- Added Physics Configuration option. This makes tweaking the physics system to suit your needs easier.
+- Added Physics Configuration option. This makes tweaking the physics system to 
+  suit your needs easier.
 - Click and doubleClick events.
 - Initial zoom bugfix.
 - Directions for Hierarchical layout.
@@ -170,7 +180,8 @@ http://visjs.org
 - Performance improvements.
 - Fixed scroll to zoom not working on IE in standards mode.
 - Added hierarchical layout option.
-- Overhauled physics system, now using Barnes-Hut simulation by default. Great performance gains.
+- Overhauled physics system, now using Barnes-Hut simulation by default. Great 
+  performance gains.
 - Modified clustering system to give better results.
 - Adaptive performance system to increase visual performance (60fps target).
 

docs/timeline.html

@@ -633,6 +633,19 @@ var options = {
     <th>Description</th>
   </tr>
 
+  <tr>
+    <td>clear([what])</td>
+    <td>none</td>
+    <td>
+      Clear the Timeline. An object can be passed specifying which sections to clear: items, groups,
+      and/or options. By Default, items, groups and options are cleared, i.e. <code>what = {items: true, groups: true, options: true}</code>. Example usage:
+
+<pre class="prettyprint lang-js">timeline.clear();                // clear items, groups, and options
+timeline.clear({options: true}); // clear options only
+</pre>
+    </td>
+  </tr>
+
   <tr>
     <td>fit()</td>
     <td>none</td>

src/timeline/Timeline.js

@@ -11,7 +11,7 @@ function Timeline (container, items, options) {
 
   var me = this;
   var now = moment().hours(0).minutes(0).seconds(0).milliseconds(0);
-  this.options = {
+  this.defaultOptions = {
     orientation: 'bottom',
     direction: 'horizontal', // 'horizontal' or 'vertical'
     autoResize: true,
@@ -25,7 +25,6 @@ function Timeline (container, items, options) {
     },
 
     selectable: true,
-    snap: null, // will be specified after timeaxis is created
 
     min: null,
     max: null,
@@ -39,6 +38,13 @@ function Timeline (container, items, options) {
     showCurrentTime: false,
     showCustomTime: false,
 
+    groupOrder: null,
+
+    width: null,
+    height: null,
+    maxHeight: null,
+    minHeight: null,
+
     type: 'box',
     align: 'center',
     margin: {
@@ -58,11 +64,17 @@ function Timeline (container, items, options) {
     },
     onRemove: function (item, callback) {
       callback(item);
-    },
+    }
+  };
+
+  this.options = {};
+  util.deepExtend(this.options, this.defaultOptions);
+  util.deepExtend(this.options, {
+    snap: null, // will be specified after timeaxis is created
 
     toScreen: me._toScreen.bind(me),
     toTime: me._toTime.bind(me)
-  };
+  });
 
   // root panel
   var rootOptions = util.extend(Object.create(this.options), {
@@ -280,7 +292,7 @@ Emitter(Timeline.prototype);
  * @param {Object} options  TODO: describe the available options
  */
 Timeline.prototype.setOptions = function (options) {
-  util.extend(this.options, options);
+  util.deepExtend(this.options, options);
 
   if ('editable' in options) {
     var isBoolean = typeof options.editable === 'boolean';
@@ -439,6 +451,33 @@ Timeline.prototype.setGroups = function setGroups(groups) {
   this.itemSet.setGroups(newDataSet);
 };
 
+/**
+ * Clear the Timeline. By Default, items, groups and options are cleared.
+ * Example usage:
+ *
+ *     timeline.clear();                // clear items, groups, and options
+ *     timeline.clear({options: true}); // clear options only
+ *
+ * @param {Object} [what]      Optionally specify what to clear. By default:
+ *                             {items: true, groups: true, options: true}
+ */
+Timeline.prototype.clear = function clear(what) {
+  // clear items
+  if (!what || what.items) {
+    this.setItems(null);
+  }
+
+  // clear groups
+  if (!what || what.groups) {
+    this.setGroups(null);
+  }
+
+  // clear options
+  if (!what || what.options) {
+    this.setOptions(this.defaultOptions);
+  }
+};
+
 /**
  * Set Timeline window such that it fits all items
  */

src/util.js

@@ -97,6 +97,40 @@ util.extend = function (a, b) {
   return a;
 };
 
+/**
+ * Deep extend an object a with the properties of object b
+ * @param {Object} a
+ * @param {Object} b
+ * @returns {Object}
+ */
+util.deepExtend = function deepExtend (a, b) {
+  // TODO: add support for Arrays to deepExtend
+  if (Array.isArray(b)) {
+    throw new TypeError('Arrays are not supported by deepExtend');
+  }
+
+  for (var prop in b) {
+    if (b.hasOwnProperty(prop)) {
+      if (b[prop] && b[prop].constructor === Object) {
+        if (a[prop] === undefined) {
+          a[prop] = {};
+        }
+        if (a[prop].constructor === Object) {
+          deepExtend(a[prop], b[prop]);
+        }
+        else {
+          a[prop] = b[prop];
+        }
+      } else if (Array.isArray(b[prop])) {
+        throw new TypeError('Arrays are not supported by deepExtend');
+      } else {
+        a[prop] = b[prop];
+      }
+    }
+  }
+  return a;
+};
+
 /**
  * Test whether all elements in two arrays are equal.
  * @param {Array} a