Rather than producing separate files for each module, the default build now
produces a single file. This should encourage better page-load performance as
the files were relatively small. Also, it's easier to deal with only one file
rather than many, especially if you're not quite sure what the dependencies are.
You may still create minimized builds, if you don't want every feature.
This commit also demotes the chart components to the examples directory, rather
than keeping them as part of the core library. As always, D3 is not a charting
library, and these were ever only intended to serve as examples.
The data join is now specified as a single function of data, as with all other
properties. This allows the key to be computed on the previously-bound data,
rather than requiring the key to be serialized into the DOM (say, as an
attribute). In the case that there is no previously-bound data, it is still
possible to access the associated node as the `this` context.
The `enter` operator no longer performs an append. For symmetry with the `exit`
operator, you must call `append` after obtaining the entering selection. This
requires a tiny bit more code, but should make the code more clear. Also, it
provides an opportunity to use a different instantiation operator, such as the
new `insert` operator. This takes a second argument, which is a selector for the
insert-before reference element. For example, the selector ":first-child" will
prepend nodes.
The `empty` operator allows you to query whether a selection is empty (i.e.,
contains zero matching nodes).
We now use the same property accessors (startAngle, endAngle and radius) for
two source and target objects. Note that you don't have to structure your data
hierarchically; you can define a source and target accessor that restructures
the data on the fly.
Mike Bostock
Kristofer Monisit
Jason Davies