feat(alternate-markers): Implement alternate markers

[julien]

Issue

#208

Details

Solution for alternate markers feature.

[coveralls]

Changes Unknown when pulling 06f23a1 on julien:alternate-markers into ** on naver:master**.

[netil]

IMO, touching whole defs isn't really good idea. There will be more efficient approach on this? Just appending the necessary node?

[julien]

@netil you're right.
I've updated this function to use defs.node().appendChild instead.
Tell me what you think

[netil]

When set the exact ID value, there's a possibility having some collision if there're more than one chart instance in same page.

As you can see the node constructed, others having ID with prefixed bb-${datetime} format.
You can prefix with the $$.clipId.

billboard.js/src/internals/ChartInternal.js

Line 85 in 9f2eb7e

$$.clipId = `bb-${+new Date()}-clip`;

Maybe in this case you need to change like this way.

$$.dtPrefix = `bb-${+new Date()}`;
$$.clipId = `${dtPrefix}-clip`;

[julien]

@netil thanks! I'll use this instead

[netil]

The interface usability was improved a lot since the last PR!
I think there're few issues remaining to get merged.

If couldn't be done before Friday, maybe we can set this feature as "experimental".

Let me know any thoughts on this. 👍

[netil]

When the flow param is truthy, it means .flow() was called.
And the flow transition(animation) should happen. You can check this setting a custom data point in the demo.

• https://github.com/naver/billboard.js/blob/master/demo/demo.js#L2166

[julien]

I'll have a look and try to fix that.

[julien]

@netil I like the idea of this being merged even if it marked as "experimental".
We can always iterate and improve it.

[coveralls]

Changes Unknown when pulling f71015c on julien:alternate-markers into ** on naver:master**.

[netil]

The returned value should be a d3 transition object when it's called by .flow(). Iterating all the <circle> elements just return a selection.
Because of this difference, .flow() not work as before.

If this can't be fixed, it can't be merged.

[julien]

@netil thanks for the detailed information.

.flow() should now be working with the latest changes.

Tell me what you think when you can.

[coveralls]

Changes Unknown when pulling bfe89d4 on julien:alternate-markers into ** on naver:master**.