* Fixes issue 3321 by ensuring labels are drawn as part of initial construction of the DataAxis

* Simplify test and remove support for node 6

* Exclude test coverage from regular test runs

* Adds code coverage report the output of `npm test` and adds detailed html code coverage report using the command `npm run-script test-cov`

* Switch over to using functions in lib/ rather than dist/, so that code coverage stats are complete.

* Import vis at the top level to keep ItemSet passing

* Remove requirement for dist/vis in TimelineItemSet

* Adds tests for Popup

* Tests and sinon dependency introduced

* Code changes to modules to tighten up code

* Corrects broken tests and adds more tests to ColorPicker

* Adds additional tests to DataSet

* Adds tests for uuid

* Removes unused functions from util

* Adds tests for utils: recursiveDomDelete, isDate, convert and isType

* removes redundant code

* Adds additional util tests

* Address spacing, and unnecessary tests

* Correct test description

* Adds isDate tests

* Adds sanity check assertions to popup destroy tests

* First working version

* Fix completed for jsdom getContext() issue

* Fixed commenting for review

* Network: DRY code in Label for parsing markup

This gets rid of a major eyesore for me. The accumulator object was identical for HTML and  Markdown.

In addition, the parsing has been refactored. Common elements have been DRY'd and the logic of the parsing has been made more comprehensible.

* Added suggestion @mbroad wrt regexp precompile

* Fixed linting

* Adds code coverage report the output of `npm test` and adds detailed html code coverage report using the command `npm run-script test-cov`

* Switch over to using functions in lib/ rather than dist/, so that code coverage stats are complete.

* Import vis at the top level to keep ItemSet passing

* Remove requirement for dist/vis in TimelineItemSet

* Network: preload images in options for all shape types

Fixes #3532

If the images option is set, preload it, even if the node shape is not `image` or `circularImage`.
This needs to be done because the user can switch to an image shape later, as is happening in the issue.
Option `image` is only mandatory for the image shapes.

There is no unit test for this, because it would need a mock object for Image and I didn't succeed in creating/finding one.

* Network: Handle null data gracefully

During testing I discovered that passing `null` for network data leads to a thrown error.
This adds a guard to prevent it, plus unit tests for regression.

* Use mock canvas object replacing `canvas`

Fixes #3515.

A mock canvas object is added to the unit tests, which makes usage of module `canvas` voluntary.

The issue with `canvas` is that it requires an external dependency to `cairo`. This complicates setting up a develop environment for `vis.js`

- Removed `canvas` from `package.json`
- Added section to README.md with instructions on how to install `canvas` instead.

* Removed debugger statements

* Updates for review

* Fixes for review

* Network: Prevent crash when dataChanged is triggered during initial setting of options

Fixes #3562.

Options `hidden` and `physics` can emit a `_dataChanged` event within `setOptions()`.
If this happens when setting options during the initialization of the `Network` instance, this leads
to an error thrown, because there is no DataSet instance  connected yet to the instance.

This bug was introduced in `v4.21.0`. Unit tests have been added for this case.

* Edited comment

Fixes #3543.

None of the options passed in any of the API calls should change the options. This has been registered with issue #3548.

* Network: Retain constraint values in label font handling

Fixes #3517.

Due to changed logic in the label font handling, the option values for `widthConstraint` and `heightConstraint` were overwritten.
The fix is in effect a reversal of two code lines: parsing constraint options should come *after* parsing (multi)font options.

Further changes:

- Additional 1-liner fix: constraint values were not copied for edge-instance specific options.
- Small refactoriing of `Label#constrain()` in order to separate concerns
- Added unit test for regression testing of this issue.

This leads to the curious observation that, while the actual change is two lines of source code, this resulted in a +-150 line regression test.

* Made unit test more linear, removed tabs

* Made 'enhanced subset' of unit test

* Removed TODO from comment

* Culled redundant nodes from unit test

* Cleaned up some whitespace and added test for issue

* Checking for proper removal, better comments and whitespace cleanup

* Network: Add extra check on null value during label handling

This fixes an oversight in #3486. Unit tests added, not only for null labels, but for all weird label values I could thing of.

* Enhanced unit tests, adjusted label check

* The next fix on Travis unit test failure

This is the next escalation on the war against the Travis unit tests failing (which came into being by yours truly).
By accident, I could recreate the unit test failure on my development machine. This led to a more directed effort to
squash the bug.

The insight here is that test `(window === undefined)` fails, but `(typeof window === 'undefined`)` succeeds. This undoubtedly has to do with the special status `window` has as a global object.

Changes:

- Added check on presence of `window` in `Canvas._requestNextFrame()`, fixed local source errors.
- Added catch clause in `CanvasRendered._determinePixelRatio()`
- small fix: raised timeout for the network `worldCup2014` unit test

* Preliminary refactoring in utils.js

* Added unit tests for extend routines, commenting and small fixes

* More unit tests for extend routines

* - Completed unit tests for extend routines in
- Small fixes and cleanup in `util.js`
- Removed `util.protoExtend()`, not used anywhere

* Added unit tests for known font options

* Interim save before trying out another proto chain strategy

* Fixed problem in first example #3408

* Removed silly file that shouldn't be there

* Added unit test for multi-fonts

* Comment edits

* Verufy unit tests, small adjustments for groups

* Further work on getting unit tests to work. PARTS NEED TO BE CLEANED UP!

* Further tweaks to get unit tests working

* All unit tests passing

* Fixes due to linting

* Small edits

* Removed prototype handling from font pile

* Fixes during testing examples of #3408

* Added unit test for edge labels, small fixes

* Added unit tests for shorthand string fonts; some tests still failing

* All unit tests pass

* Removed Label.parseOptions()

* Completed shorthand font tests, code cleanup, fixed choosify for edges

* Addressed review comments

* Addressed review comments, cleanup

* Refactoring of label splitting; new unit test still failing.

* Label acc size calculations to separate methods.

* Final fixes and cleanup

* Added unit test for Array.prototype mangling - first passing version

* Enhanced unit test for prototype stressing to catch more illegal for-in loops

* Fixed all for-in linting violations

* The next fix on Travis unit test failure

This is the next escalation on the war against the Travis unit tests failing (which came into being by yours truly).
By accident, I could recreate the unit test failure on my development machine. This led to a more directed effort to
squash the bug.

The insight here is that test `(window === undefined)` fails, but `(typeof window === 'undefined`)` succeeds. This undoubtedly has to do with the special status `window` has as a global object.

Changes:

- Added check on presence of `window` in `Canvas._requestNextFrame()`, fixed local source errors.
- Added catch clause in `CanvasRendered._determinePixelRatio()`
- small fix: raised timeout for the network `worldCup2014` unit test

* Preliminary refactoring in utils.js

* Added unit tests for extend routines, commenting and small fixes

* More unit tests for extend routines

* - Completed unit tests for extend routines in
- Small fixes and cleanup in `util.js`
- Removed `util.protoExtend()`, not used anywhere

* Added unit tests for known font options

* Network: Fixes sorting on Layout sorting, refactoring.

Fix for #3403

Chromium has divergent behaviour on sorting of `undefined` values, a check has been added for these.

The fix itself is small, it adds a check on `undefined` in the sorting function(s).

In addition:

- Fixed off-by-one error on tree index
- Refactored away checks on visibility by replacing `_isVisible()` with a Strategy pattern for direction

The latter removes a long-standing eyesore in `LayoutManager`; it's probably also faster.

There is some hope that these fixes will improve the hierarchical layout initialization, which has had
problems for quite a while.

* reformat code block

* Add next attempt to fix Travis unit test bug

* Fix unit test - timeout

* Adjustments for comment reviews

* Moved direction strategies to separate module; added fix for 'window is undefined'

This is the next escalation on the war against the Travis unit tests failing (which came into being by yours truly).
By accident, I could recreate the unit test failure on my development machine. This led to a more directed effort to
squash the bug.

The insight here is that test `(window === undefined)` fails, but `(typeof window === 'undefined`)` succeeds. This undoubtedly has to do with the special status `window` has as a global object.

Changes:

- Added check on presence of `window` in `Canvas._requestNextFrame()`, fixed local source errors.
- Added catch clause in `CanvasRendered._determinePixelRatio()`
- small fix: raised timeout for the network `worldCup2014` unit test

* added hexagon shape to the node.

* Updated function for hexagon shape.js

* Modifid the shape login for hexagon

* Remove this.translate from the Shape.js for hexagon

* updated hexagon draw logic

* Fixed code review comments and update the branch

* Updated changes in test.js

* Adds unit tests for add, setOptions and on/off

* removes extraneous return value name in @throws tag of jsdoc

* First fix for opening clusters, added unit tests

* Added opening of child cluster to parent cluster

* Added more tests for multi-level clusters

* Commenting fixes

* Added unit tests for option allowSingleNodeCluster, fixes due to that

* Added test for allowSingleNodeCluster with nested clusters

* Fixes due to linting

* Removed TODO from code

Fix for #3367

Changes:

- Clustered nodes with shared connections are added to the same cluster
- joinCondition value `null` handled as `undefined`
- Fixed bug on adding clusters if joinCondition present and returns true

Unit tests have been added to `Network.test.js` for these changes.

* Added commenting for options, refactored choosify()

* Refactored updateLabelModule()

* added comment at node creation

* Completed fix for #3350

* parseOptions() different handling for bridged/extended; unit tests for reversal of options

* Fixes on linting and unit testing

* Enable unit testing for module Network

Adds mocks for certain components, in order to let module `Network` be run in unit tests.

Changes:

- Create a mock object for `hammer.js` when running browserless. The inspiration is taken from [here](https://github.com/uber/deck.gl/pull/658)
- Create a mock function for `window.requestAnimationFrame()` when running browserless in `network/modules/CanvasRenderer.js`
- Added unit test for `Network` to show that unit testing for it now works
- Fixed naming of container in `test/Graph3d.test.js`

Since `hammer.js` is also used in other modules, this fix is potentially an enabler for full-module unit tests for those as well.

* Cleanup unit test Network

* Fix for unit test

* Added example networks to unit test

* Fix error in loading disassemblerExample

* Network unit test final fixes

* Adjusted comments

* First working version of updating clustered edge

* Added fix for #1315 as well

* Enable unit testing for module Network

Adds mocks for certain components, in order to let module `Network` be run in unit tests.

Changes:

- Create a mock object for `hammer.js` when running browserless. The inspiration is taken from [here](https://github.com/uber/deck.gl/pull/658)
- Create a mock function for `window.requestAnimationFrame()` when running browserless in `network/modules/CanvasRenderer.js`
- Added unit test for `Network` to show that unit testing for it now works
- Fixed naming of container in `test/Graph3d.test.js`

Since `hammer.js` is also used in other modules, this fix is potentially an enabler for full-module unit tests for those as well.

* Cleanup unit test Network

* Added unit test for fix issue #1218

* Adding test for #1315 - Interim save

* Completed unit test and fixes for #1315

* Added fixes for #1291

* Added unit test for #1219

* Added header comment for Clustering.js, small fixes

* Fix for unit test

* Added example networks to unit test

* Fix error in loading disassemblerExample

* Network unit test final fixes

* Fixes for linting

* Fixed essential typo

* Fixed linting error

* Fixed unit test

* Fixed unit test again

* Proof of concept with copied options + handling from network

* Added unit test for Graph3d, for checking default syntax; completed def's of all options, autoByDefault not handled yet.

* Fixes for options in playground example

* Added onclick options to graph3d documentation

* Fixes in graph3d examples

* Final fixes for option definitions in Graph3d

* Fixed handling of 'undefined' in options, enhanced graph3d unit test

* Disabled console output in graph3d unit test

* Upgrade webpack module

* Fix mergeOptions() and add unit tests

* Removed comment

* Code cleanup, for better understanding

* Further refactoring; text processing to blocks in separate method

* Added unit test for labels - tests standard text and html tags

* Labels added unit tests for markdown

* Further refactoring; made multi and regular handling more congruent

* Interim save, not there yet

* Unit tests done, first working version

* Added test case with two big words

* Code cleanup

* Break up huge words into lines.

* Restore unrelated code change

* Added unit test for Validator, minimum viable version.

* Added test-console to package list

* Completed minimum viable unit test for Validator

* Added Validator unit test for explicit 'undefined'

* Add unit tests for Graph3D issue

This adds a unit test for PR #3255 which fixes #3251.
The unit test will fail without the PR merged.

**NOTE:** This also adds module `canvas`, required for the unit test. This module
proved to be quite fickly to install properly. During reviewing, please pay special
attention to the proper installation of this modul. I.e. do following to test:

```
> npm install                      # If no errors, continue
> npm test /tests/Graph3D.test.js  # Run unit test isolated
```

* Fix for travis-cl

* Add giflib to travis test definition

* Add libgif to travis test definition - take 2

* Proper setup and teardown for jsdom-global

* Minor fixes and cleanup

* Fix for timeline TimeStep.roundToMinor - resolving issue #3105

* Adding some tests for TimeStep

* Properly handle newline escape sequences in strings for DOT

* Adjust comments in code

This takes a more robust approach to produce the list of class names.

Somewhat more complicated setup, associated with the need for a real window.

Clean up and centralise edit status for Timeline Items.

* maximum width constraints must be violated by long words. Fixes #2604.

* chore: moved examples/network/_tests/maximumWidthEdgeCase.html to test/network/

Fixes default end, and reduces duplicated code. Adds tests.

* Should fix issue #2100 and fix another issue we discovered around clusterByConnection leaving phantom edges.
* fixed a wrong variable name
* fixed DataView.test.js assert
* Update Canvas.js
* remove whitespace; remove end of file newline on Canvas.js
* strip end of file newlines
* fixed styling. spacing, semicolons, line length

- Added parentCentralization option for hierarchical layout.

added example. Improved handling of options for hierarchical view.