Punch card Chart: v5 Static

• Version 5 D3
• with Squares rather than Circles (that are harder to compare)

A vanilla HTML implementation of Chris Henrick PunchCard tutorial "D3JS v4 General Update Pattern: Punchcard Chart"

https://clhenrick.io/d3-v4-general-update-pattern-punchcard-chart/

bl.ock: https://bl.ocks.org/clhenrick/2b6b5360748a06b26bfd50d96998b741