D3.js Data Binding

D3.js (Data-Driven Documents) is a framework used to better show case data, whether it be through animations, transitions, or proper charting. D3 allows arbitrary data to be bound to the DOM, better allowing transitions and user interaction with the data itself.

As data can change on the fly, say from a live feed of data, D3 needs to quickly modify data that it bound to the DOM. Previously, D3 used three selection methods to take care of this work flow: Enter, Exit, and Update.

.enter()

This function pairs spare nodes with data incoming, new data. The new part is important. If a datum is unchanged in the incoming data, it is used by a different function Update. Instead of completely swapping out an entire data set with the updated data set, Enter only selects the new or changed data.

.exit()

This function does the opposite. Any data that is included in the old data set but not in the updated data set will get selected by the Exit function. this removes the data bound to the nodes (but does not remove the nodes) and allows these nodes to be used in the future

.update()

Finally, this function ensures that you are selecting the nodes that are currently bound to data. These three functions allow the user to select the nodes and data they want in whichever order they choose. This can help in making transitions and interaction with data more seamless and responsive. If you want the new data to be compared to the old data, different…