How do I control the display order of traces in plotly.js?

Question

I have a large number of trace lines being displayed. 50-200 typically. I am comparing historical data to simulated data. I want to highlight a single simulated traceline by selection via a different color. All of this works fine.

However, the trace line being shown is sometimes hidden by the large number of other lines. Is there a way to force the specified trace to be drawn on top of the others, aside from redrawing the entire plot and adding that line last? Some sort of z-index equivalent or "bring to front" mechanism?

Answer 1

Perhaps this useful to other Plotly users as well. The snippet pushed trace 7 to the foreground using Plotly's react function.

var foreground = 7; //trace which is pushed to the foreground

//generate some random data
var trace1 = {
  x: [1, 2, 3, 4],
  y: [1, 2, 0.5, 1.5],
  type: 'lines',
  name: 'trace 0',
  line: {
width: 2
  }
};

var data = [trace1];
var i = 0;
var j = 0;
for (i = 1; i < 10; i += 1) {
  var trace = {
x: [],
y: [],
type: 'lines',
name: 'trace ' + i,
'line': {
  'width': 2
}
  };
  for (j = 0; j < trace1.x.length; j += 1) {
trace.x.push(trace1.x[j])
trace.y.push(trace1.y[j] + Math.random())
  }
  data.push(trace);
}

var buttonForeground = document.getElementById("foreground");
var buttonReset = document.getElementById("reset");

var div = document.getElementById('myDiv');
Plotly.newPlot(div, data);

buttonReset.disabled = true;
buttonForeground.onclick = function() {
  var temp = data[foreground];
  data[foreground] = data[data.length - 1];
  data[data.length - 1] = temp;
  data[data.length - 1]['line']['width'] = 5;
  Plotly.react(div, data);

  switchButtons();
};

document.getElementById("reset").onclick = function() {
  var temp = data[data.length - 1];
  data[data.length - 1] = data[foreground];
  data[foreground] = temp;
  data[foreground]['line']['width'] = 2;
  Plotly.react(div, data, {});
  
  switchButtons();
};

function switchButtons() {
  buttonForeground.disabled = !buttonForeground.disabled;
  buttonReset.disabled = !buttonReset.disabled;
}

<script src="https://cdn.plot.ly/plotly-latest.min.js"></script>
<div id="myDiv" style="width: 480px; height: 400px;"></div>
<button type="button" id='foreground'>Foreground</button>
<button type="button" id='reset'>Reset</button>