How to draw polygon in d3.js?

@darrion.kuhn 

To draw a polygon in d3.js, you can use the d3.line() function to generate a path data string for the points of the polygon, and then use the d3.select() and d3.append() functions to create an SVG element to render the polygon.

Here's an example code snippet to draw a polygon with 5 points:

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// Define the points of the polygon
const polygonData = [
  [100, 100],
  [200, 100],
  [200, 200],
  [150, 250],
  [100, 200]
];

// Create a path data string for the points
const lineGenerator = d3.line()
  .x(d => d[0])
  .y(d => d[1]);
const pathData = lineGenerator(polygonData) + "Z";

// Create a SVG element and append the polygon path
const svg = d3.select("body").append("svg")
  .attr("width", 400)
  .attr("height", 400);
svg.append("path")
  .attr("d", pathData)
  .attr("fill", "lightblue")
  .attr("stroke", "black")
  .attr("stroke-width", 2);

In this code snippet, we first define the points of the polygon in the polygonData array. We then use the d3.line() function to create a line generator that will generate a path data string for the points. We call the generator with the polygonData array to get the path data and add a "Z" at the end to close the polygon.

Next, we create an SVG element using d3.select().append() and set its width and height attributes. We then append a <path> element to the SVG, set its d attribute to the path data string we generated, and set the fill, stroke, and stroke-width attributes to define the appearance of the polygon.

You can customize the polygon by changing the points in the polygonData array and modifying the attributes of the SVG path element.