Error Bars in JavaScript

How to add error bars to a D3.js-based line, scatter, or bar chart. Seven examples of symmetric, asymmetric, horizontal, and colored error bars.

Basic Symmetric Error Bars

var data = [
  {
    x: [0, 1, 2],
    y: [6, 10, 2],
    error_y: {
      type: 'data',
      array: [1, 2, 3],
      visible: true
    },
    type: 'scatter'
  }
];
Plotly.newPlot('myDiv', data);

Bar Chart with Error Bars

var trace1 = {
  x: ['Trial 1', 'Trial 2', 'Trial 3'],
  y: [3, 6, 4],
  name: 'Control',
  error_y: {
    type: 'data',
    array: [1, 0.5, 1.5],
    visible: true
  },
  type: 'bar'
};
var trace2 = {
  x: ['Trial 1', 'Trial 2', 'Trial 3'],
  y: [4, 7, 3],
  name: 'Experimental',
  error_y: {
    type: 'data',
    array: [0.5, 1, 2],
    visible: true
  },
  type: 'bar'
};
var data = [trace1, trace2];
var layout = {barmode: 'group'};
Plotly.newPlot('myDiv', data, layout);

Horizontal Error Bars

var data = [
  {
    x: [1, 2, 3, 4],
    y: [2, 1, 3, 4],
    error_x: {
      type: 'percent',
      value: 10
    },
    type: 'scatter'
  }
];
Plotly.newPlot('myDiv', data);

Asymmetric Error Bars

var data = [
  {
    x: [1, 2, 3, 4],
    y: [2, 1, 3, 4],
    error_y: {
      type: 'data',
      symmetric: false,
      array: [0.1, 0.2, 0.1, 0.1],
      arrayminus: [0.2, 0.4, 1, 0.2]
    },
    type: 'scatter'
  }
];
Plotly.newPlot('myDiv', data);

Colored and Styled Error Bars

function linspace(a,b,n) {
  return Plotly.d3.range(n).map(function(i){return a+i*(b-a)/(n-1);});
}
x_theo = linspace(-4, 4, 100)
sincx = Math.sin(x_theo) / x_theo
var x = [-3.8, -3.03, -1.91, -1.46, -0.89, -0.24, -0.0, 0.41, 0.89, 1.01, 1.91, 2.28, 2.79, 3.56]
var y = [-0.02, 0.04, -0.01, -0.27, 0.36, 0.75, 1.03, 0.65, 0.28, 0.02, -0.11, 0.16, 0.04, -0.15]

var trace1 = {
  x: x_theo,
  y: sincx,
  name: 'sinc(x)',
  type: 'scatter'
};
var trace2 = {
  x: x,
  y: y,
  mode: 'markers',
  name: 'measured',
  error_y: {
    type: 'constant',
    value: 0.1,
    color: '#85144B',
    thickness: 1.5,
    width: 3,
    opacity: 1
  },
  error_x: {
    type: 'constant',
    value: 0.2,
    color: '#85144B',
    thickness: 1.5,
    width: 3,
    opacity: 1
  },
  marker: {
    color: '#85144B',
    size: 8
  },
  type: 'scatter'
};
var data = [trace1, trace2];
Plotly.newPlot('myDiv', data, {}, {showSendToCloud: true});

Error Bars as a Percentage of the y-Value

var data = [
  {
    x: [0, 1, 2],
    y: [6, 10, 2],
    error_y: {
      type: 'percent',
      value: 50,
      visible: true
    },
    type: 'scatter'
  }
];
Plotly.newPlot('myDiv', data);

Asymmetric Error Bars with a Constant Offset

var data = [
  {
    x: [1, 2, 3, 4],
    y: [2, 1, 3, 4],
    error_y: {
      type: 'percent',
      symmetric: false,
      value: 15,
      valueminus: 25
    },
    type: 'scatter'
  }
];
Plotly.newPlot('myDiv', data);

plotly.js runs on all SVG-compatible browsers