United States Postage Rate

An implementation in D3 of Figure 4-42 “Step chart showing change in postage rate” in “Visualize This” by Nathan Yau.

Both the tickFormat function used for the x axis and the function used to render the amounts use a directly executed JavaScript function. This function returns another JavaScript function and creates a closure on the first variable, allowing them to have a specific format for the first option in the dataset.

Issues:

• The tickmark for 2001 renders as ‘01 instead of 2001