Just look at this beauty:

This is a bar chart made with plotlyjs which relies on D3 under the hood.

<head>
  <!-- Plotly.js -->
  <script src="https://cdn.plot.ly/plotly-latest.min.js"></script>
  <!-- Numeric JS -->
  <script src="https://cdnjs.cloudflare.com/ajax/libs/numeric/1.2.6/numeric.min.js"></script>
</head>

<body>
  
  <div id="myDiv"><!-- Plotly chart will be drawn inside this DIV --></div>
  <script>
    <!-- JAVASCRIPT CODE GOES HERE -->


var data = [{
  values: [19, 26, 55],
  labels: ['Residential', 'Non-Residential', 'Utility'],
  type: 'pie'
}];

Plotly.newPlot('myDiv', data, {}, {responsive: true});

  </script>
</body>

How is this Special?

There are many ways to draw a pie chart. With D3, however, they can be drawn as HTML and as vector graphics that are beautiful and responsive (to screen resize). See them here in revealjs slides. Full view.