Smoothed D3.js Radar Chart
This smoothed D3.js radar chart compares smartphone attributes—such as battery life, brand, and contract cost—across three phone models (iPhone, Samsung, Nokia). The visualization uses circular grid levels with percentage labels, radiating axes, and filled, semi-transparent polygons with rounded strokes to represent each product’s profile. Built with D3 v4, the code leverages `d3.scaleOrdinal` for color, `d3.scaleLinear` for the radial scale, and SVG elements like circles and paths to render the chart, complete with a glow filter and interactive hover tooltips.