Ian Johnson is the author of Tributary - an open source live-coding environment designed for prototyping data visualizations with D3. He also co-organizes the SF Bay Area d3 Meetup and makes educational D3 videos.
Data Visualization with D3
Ian begins binding the chart interactions with each other. The scatter plot should only show data for the range displayed in the brush. To do this, he sets up an event listener in the main application to listen for changes in the brush.