Today’s “from scratch” example with D3 is a must-have element of any data visualisation portfolio: a line chart. Line charts are great of visualizing changes in data over time. Just as in the previous posts in the series, my visualisation is a variation of a piece of code I found on the web. I started with a basic template created by Mike Bostock and then re-worked some of its elements to boost its usability & readability. As with the previous examples, all code can be downloaded, reused, adjusted, and it scales up and down to include extra data series or to remove one.