d3-learning

Selections:

Selectios are a subclass of array. it provides methods to manipulate selected elements, such as setting attributes and styles.

selection.each:
selection.filter:
selection.sort:

Selections are arrays of arrays of elements:

d3.select(): select a selection with one group

d3.selectAll():

data is not a property of the selection, but a property of its elements.

When binding data to a selection, the data is stored in the DOM rather than in the selection.

data is persistent while selections can be considered transient.

Data is bound to elements one of several ways:

1. Joined to groups of elements via selection.data.
2. Assigned to individual elements via selection.datum.
3. Inherited from a parent via append, insert, or select.