This example demonstrates a minimal line graph that initially displays a placeholder text message and switches to the word “Update” when a button is clicked. Built with D3 v4 and SVG, the visualization uses a custom JavaScript class, `LineGraph`, to manage the graph’s creation and update states. The code appends an SVG element to a container div and uses d3 selection methods like `d3.select` and `attr` to style text elements. Despite referencing a `data` array, the graph does not currently render any actual data points, focusing instead on the interaction pattern between the button and the chart’s update method.