<head>
  <script src="https://cdn.plot.ly/plotly-latest.min.js"></script>
</head>
<body>
  <div id="graph"></div>
</body>
Plotly.newPlot('graph', [{
  y: [1, 2, 1, 3, 2],
  line: {shape: 'spline'}
}], {
  shapes: [{
    type: 'line',
    xref: 'paper',
    x0: 0,
    x1: 1,
    yref: 'y',
    y0: 2,
    y1: 2
  }]
})

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External JavaScript

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