# Histograms in JavaScript

How to make a D3.js-based histogram in JavaScript. Seven examples of colored, horizontal, and normal histogram bar charts.

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### Basic Histogram

var x = [];
for (var i = 0; i < 500; i ++) {
x[i] = Math.random();
}

var trace = {
x: x,
type: 'histogram',
};
var data = [trace];
Plotly.newPlot('myDiv', data);


### Horizontal Histogram

var y = [];
for (var i = 0; i < 500; i ++) {
y[i] = Math.random();
}

var data = [
{
y: y,
type: 'histogram',
marker: {
color: 'pink',
},
}
];
Plotly.newPlot('myDiv', data);


### Overlaid Histogram

var x1 = [];
var x2 = [];
for (var i = 1; i < 500; i++)
{
k = Math.random();
x1.push(Math.random() + 1);
x2.push(Math.random() + 1.1);
}
var trace1 = {
x: x1,
type: "histogram",
opacity: 0.5,
marker: {
color: 'green',
},
};
var trace2 = {
x: x2,
type: "histogram",
opacity: 0.6,
marker: {
color: 'red',
},
};

var data = [trace1, trace2];
var layout = {barmode: "overlay"};
Plotly.newPlot('myDiv', data, layout);


### Stacked Histograms

var x1 = [];
var x2 = [];
for (var i = 0; i < 500; i ++) {
x1[i] = Math.random();
x2[i] = Math.random();
}

var trace1 = {
x: x1,
type: "histogram",
};
var trace2 = {
x: x2,
type: "histogram",
};
var data = [trace1, trace2];
var layout = {barmode: "stack"};
Plotly.newPlot('myDiv', data, layout);


### Colored and Styled Histograms

var x1 = [];
var x2 = [];
var y1 = [];
var y2 = [];
for (var i = 1; i < 500; i++)
{
k = Math.random();
x1.push(k*5);
x2.push(k*10);
y1.push(k);
y2.push(k*2);
}
var trace1 = {
x: x1,
y: y1,
name: 'control',
autobinx: false,
histnorm: "count",
marker: {
color: "rgba(255, 100, 102, 0.7)",
line: {
color:  "rgba(255, 100, 102, 1)",
width: 1
}
},
opacity: 0.5,
type: "histogram",
xbins: {
end: 2.8,
size: 0.06,
start: .5
}
};
var trace2 = {
x: x2,
y: y2,
autobinx: false,
marker: {
color: "rgba(100, 200, 102, 0.7)",
line: {
color:  "rgba(100, 200, 102, 1)",
width: 1
}
},
name: "experimental",
opacity: 0.75,
type: "histogram",
xbins: {
end: 4,
size: 0.06,
start: -3.2

}
};
var data = [trace1, trace2];
var layout = {
bargap: 0.05,
bargroupgap: 0.2,
barmode: "overlay",
title: "Sampled Results",
xaxis: {title: "Value"},
yaxis: {title: "Count"}
};
Plotly.newPlot('myDiv', data, layout);


### Cumulative Histogram

var x = [];
for (var i = 0; i < 500; i ++) {
x[i] = Math.random();
}

var trace = {
x: x,
type: 'histogram',
cumulative: {enabled: true}
};
var data = [trace];
Plotly.newPlot('myDiv', data);


### Normalized Histogram

var x = [];
for (var i = 0; i < 500; i ++) {
x[i] = Math.random();
}

var data = [
{
x: x,
type: 'histogram',
histnorm: 'probability',
marker: {
color: 'rgb(255,255,100)',
},
}
];
Plotly.newPlot('myDiv', data);


### Specify Binning Function

var x = ["Apples","Apples","Apples","Oranges", "Bananas"]
var y = ["5","10","3","10","5"]

var data = [
{
histfunc: "count",
y: y,
x: x,
type: "histogram",
name: "count"
},
{
histfunc: "sum",
y: y,
x: x,
type: "histogram",
name: "sum"
}
]

Plotly.newPlot('myDiv', data)