[docs] Tree chart with arrow heads

<!DOCTYPE html>
<html class="zc-html">

<head>
  <meta charset="utf-8">
  <title>ZingGrid: Blank Grid</title>
  <script nonce="undefined" src="https://cdn.zingchart.com/zingchart.min.js"></script>
  <style>
    .chart--container {
      min-height: 450px;
      overflow: auto;
      position: relative;
      height: 100%;
      width: 100%;
    }

    .zc-ref {
      display: none;
    }
  </style>
</head>

<body class="zc-body">

  <!-- CHART CONTAINER -->
  <div id="myChart" class="chart--container">
    <a class="zc-ref" href="https://www.zingchart.com">Powered by ZingChart</a>
  </div>

  <script>
    ZC.LICENSE = ["569d52cefae586f634c54f86dc99e6a9", "b55b025e438fa8a98e32482b5f768ff5"]; // window:load event for Javascript to run after HTML
    // because this Javascript is injected into the document head
    window.addEventListener('load', () => {
      let chartData = [{
          type: 'node',
          id: 'a',
          name: 'α'
        },
        {
          type: 'node',
          id: 'b',
          name: 'β'
        },
        {
          type: 'node',
          id: 'g',
          name: 'γ'
        },
        {
          type: 'link',
          source: 'a',
          target: 'b'
        },
        {
          type: 'link',
          source: 'a',
          target: 'g'
        },

        {
          type: 'node',
          id: 'd',
          name: 'δ'
        },
        {
          type: 'node',
          id: 'e',
          name: 'ε'
        },
        {
          type: 'node',
          id: 'z',
          name: 'ζ'
        },
        {
          type: 'node',
          id: 'th',
          name: 'θ'
        },
        {
          type: 'link',
          source: 'd',
          target: 'e'
        },
        {
          type: 'link',
          source: 'e',
          target: 'z'
        },
        {
          type: 'link',
          source: 'z',
          target: 'th'
        },
        {
          type: 'link',
          source: 'th',
          target: 'd'
        },

        {
          type: 'node',
          id: 'i',
          name: 'ι'
        },
        {
          type: 'node',
          id: 'k',
          name: 'κ'
        },
        {
          type: 'link',
          source: 'i',
          target: 'k'
        },
      ];

      let chartConfig = {
        type: 'tree',
        plotarea: {
          margin: '50px'
        },
        options: {
          aspect: 'graph',
          springLength: 75,
          attractionConstant: 0.8,
          repulsionConstant: 4000,
          repulsionDistanceFactor: 20,
          link: {
            lineColor: '#000',
            lineWidth: '2px',
            endPoint: {
              type: 'triangle',
              width: '7px',
              length: '10px',
              borderColor: '#505050',
              backgroundColor: '#505050'
            },
          },
          'link[source-i]': {
            startPoint: {
              type: 'triangle',
              width: '7px',
              length: '10px',
              borderColor: '#505050',
              backgroundColor: '#505050'
            },
          },
          node: {
            size: 24,
            borderWidth: '3px',
            borderColor: '#dedede',
            backgroundColor: '#fff',
            backgroundRepeat: 'no-repeat',
            backgroundScale: 0.75,
            label: {
              color: '#505050',
              fontSize: '18px'
            }
          },
        },
        series: chartData
      };

      zingchart.render({
        id: 'myChart',
        width: '100%',
        height: '100%',
        data: chartConfig
      });

    });
  </script>
</body>

</html>

<!DOCTYPE html>
<html class="zc-html">

<head>
  <meta charset="utf-8">
  <title>ZingGrid: Blank Grid</title>
  <script src="https://cdn.zingchart.com/zingchart.min.js"></script>
</head>

<body class="zc-body">

  <!-- CHART CONTAINER -->
  <div id="myChart" class="chart--container">
    <a class="zc-ref" href="https://www.zingchart.com">Powered by ZingChart</a>
  </div>

</body>

</html>

.chart--container {
  min-height: 450px;
  overflow: auto;
  position: relative;
  height: 100%;
  width: 100%;
}

.zc-ref {
  display: none;
}

// window:load event for Javascript to run after HTML
// because this Javascript is injected into the document head
window.addEventListener('load', () => {
  let chartData = [{
      type: 'node',
      id: 'a',
      name: 'α'
    },
    {
      type: 'node',
      id: 'b',
      name: 'β'
    },
    {
      type: 'node',
      id: 'g',
      name: 'γ'
    },
    {
      type: 'link',
      source: 'a',
      target: 'b'
    },
    {
      type: 'link',
      source: 'a',
      target: 'g'
    },

    {
      type: 'node',
      id: 'd',
      name: 'δ'
    },
    {
      type: 'node',
      id: 'e',
      name: 'ε'
    },
    {
      type: 'node',
      id: 'z',
      name: 'ζ'
    },
    {
      type: 'node',
      id: 'th',
      name: 'θ'
    },
    {
      type: 'link',
      source: 'd',
      target: 'e'
    },
    {
      type: 'link',
      source: 'e',
      target: 'z'
    },
    {
      type: 'link',
      source: 'z',
      target: 'th'
    },
    {
      type: 'link',
      source: 'th',
      target: 'd'
    },

    {
      type: 'node',
      id: 'i',
      name: 'ι'
    },
    {
      type: 'node',
      id: 'k',
      name: 'κ'
    },
    {
      type: 'link',
      source: 'i',
      target: 'k'
    },
  ];

  let chartConfig = {
    type: 'tree',
    plotarea: {
      margin: '50px'
    },
    options: {
      aspect: 'graph',
      springLength: 75,
      attractionConstant: 0.8,
      repulsionConstant: 4000,
      repulsionDistanceFactor: 20,
      link: {
        lineColor: '#000',
        lineWidth: '2px',
        endPoint: {
          type: 'triangle',
          width: '7px',
          length: '10px',
          borderColor: '#505050',
          backgroundColor: '#505050'
        },
      },
      'link[source-i]': {
        startPoint: {
          type: 'triangle',
          width: '7px',
          length: '10px',
          borderColor: '#505050',
          backgroundColor: '#505050'
        },
      },
      node: {
        size: 24,
        borderWidth: '3px',
        borderColor: '#dedede',
        backgroundColor: '#fff',
        backgroundRepeat: 'no-repeat',
        backgroundScale: 0.75,
        label: {
          color: '#505050',
          fontSize: '18px'
        }
      },
    },
    series: chartData
  };

  zingchart.render({
    id: 'myChart',
    width: '100%',
    height: '100%',
    data: chartConfig
  });

});