Browse Components
Heatmap
Spot patterns across a matrix of values.
Basic
Hover, tap or focus a mark to inspect exact values. Arrow keys move between observations.
| Observation | Morning | Midday | Evening | Night |
|---|---|---|---|---|
| Mon | 12 | 28 | 19 | 4 |
| Tue | 8 | 35 | 24 | 6 |
| Wed | 16 | 31 | 18 | 5 |
| Thu | 11 | 40 | 27 | 8 |
| Fri | 20 | 33 | 38 | 12 |
| Sat | 7 | 17 | 29 | 15 |
| Sun | 5 | 14 | 22 | 9 |
View Code
<figure class="chart" data-chart="heatmap">
<figcaption>
Weekly activity
</figcaption>
<div class="chart-data">
<table>
<caption>
Weekly activity — example data
</caption>
<thead>
<tr>
<th scope="col">
Observation
</th>
<th scope="col">
Morning
</th>
<th scope="col">
Midday
</th>
<th scope="col">
Evening
</th>
<th scope="col">
Night
</th>
</tr>
</thead>
<tbody>
<tr>
<th scope="row">
Mon
</th>
<td>
12
</td>
<td>
28
</td>
<td>
19
</td>
<td>
4
</td>
</tr>
<tr>
<th scope="row">
Tue
</th>
<td>
8
</td>
<td>
35
</td>
<td>
24
</td>
<td>
6
</td>
</tr>
<tr>
<th scope="row">
Wed
</th>
<td>
16
</td>
<td>
31
</td>
<td>
18
</td>
<td>
5
</td>
</tr>
<tr>
<th scope="row">
Thu
</th>
<td>
11
</td>
<td>
40
</td>
<td>
27
</td>
<td>
8
</td>
</tr>
<tr>
<th scope="row">
Fri
</th>
<td>
20
</td>
<td>
33
</td>
<td>
38
</td>
<td>
12
</td>
</tr>
<tr>
<th scope="row">
Sat
</th>
<td>
7
</td>
<td>
17
</td>
<td>
29
</td>
<td>
15
</td>
</tr>
<tr>
<th scope="row">
Sun
</th>
<td>
5
</td>
<td>
14
</td>
<td>
22
</td>
<td>
9
</td>
</tr>
</tbody>
</table>
</div>
</figure>Right-to-left
Labels follow the reading direction. Numeric and radial axes keep their established orientation.
| Observation | Morning | Midday | Evening | Night |
|---|---|---|---|---|
| Mon | 12 | 28 | 19 | 4 |
| Tue | 8 | 35 | 24 | 6 |
| Wed | 16 | 31 | 18 | 5 |
| Thu | 11 | 40 | 27 | 8 |
| Fri | 20 | 33 | 38 | 12 |
| Sat | 7 | 17 | 29 | 15 |
| Sun | 5 | 14 | 22 | 9 |
View Code
<figure class="chart" dir="rtl" data-chart="heatmap">
<figcaption>
Weekly activity
</figcaption>
<div class="chart-data">
<table>
<caption>
Weekly activity — example data
</caption>
<thead>
<tr>
<th scope="col">
Observation
</th>
<th scope="col">
Morning
</th>
<th scope="col">
Midday
</th>
<th scope="col">
Evening
</th>
<th scope="col">
Night
</th>
</tr>
</thead>
<tbody>
<tr>
<th scope="row">
Mon
</th>
<td>
12
</td>
<td>
28
</td>
<td>
19
</td>
<td>
4
</td>
</tr>
<tr>
<th scope="row">
Tue
</th>
<td>
8
</td>
<td>
35
</td>
<td>
24
</td>
<td>
6
</td>
</tr>
<tr>
<th scope="row">
Wed
</th>
<td>
16
</td>
<td>
31
</td>
<td>
18
</td>
<td>
5
</td>
</tr>
<tr>
<th scope="row">
Thu
</th>
<td>
11
</td>
<td>
40
</td>
<td>
27
</td>
<td>
8
</td>
</tr>
<tr>
<th scope="row">
Fri
</th>
<td>
20
</td>
<td>
33
</td>
<td>
38
</td>
<td>
12
</td>
</tr>
<tr>
<th scope="row">
Sat
</th>
<td>
7
</td>
<td>
17
</td>
<td>
29
</td>
<td>
15
</td>
</tr>
<tr>
<th scope="row">
Sun
</th>
<td>
5
</td>
<td>
14
</td>
<td>
22
</td>
<td>
9
</td>
</tr>
</tbody>
</table>
</div>
</figure>Empty data
The chart keeps its reserved space without inventing observations.
| Observation | Morning | Midday | Evening | Night |
|---|
View Code
<figure
class="chart"
data-chart-labels="["Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun"]"
data-chart="heatmap"
>
<figcaption>
Weekly activity
</figcaption>
<div class="chart-data">
<table>
<caption>
Weekly activity — example data
</caption>
<thead>
<tr>
<th scope="col">
Observation
</th>
<th scope="col">
Morning
</th>
<th scope="col">
Midday
</th>
<th scope="col">
Evening
</th>
<th scope="col">
Night
</th>
</tr>
</thead>
<tbody>
</tbody>
</table>
</div>
</figure>Installation
Download these files into the matching paths in your project, or use Create to assemble a kit. Include each dependency once. Do not also load app.css.
<link rel="stylesheet" href="/library/assets/base.css">
<link rel="stylesheet" href="/library/assets/chart-core.css">
<link rel="stylesheet" href="/library/assets/chart-plots.css">
<link rel="stylesheet" href="/library/assets/heatmap.css">
<script defer src="/library/assets/chart-core.js"></script>
<script defer src="/library/assets/chart-plots.js"></script>
<script defer src="/library/assets/heatmap.js"></script>12,194 bytes CSS including base · 16,434 bytes runtime JavaScript
Usage
Data format
Rows and columns form a matrix with up to four columns and 32 rows. Darker or brighter cells indicate higher values using a single sequential color scale. Hover or focus for exact values; compare only within the same scale.
Shared interactions
Hover, tap or focus a mark to inspect its exact value. Arrow keys, Home and End move between marks; Escape dismisses the tooltip. The source table remains available without JavaScript. Enhanced charts expose exact values through accessible marks and tooltips.
Lifecycle and themes
Load Chart Core, Chart Plots and this component module. Theme tokens supply colors in light and dark modes. Use layoutCharts.refresh(root) after changing the table and destroy(root) before unmounting. Wide charts scroll within their frame.
Building with AI? The AI Manifest has these notes and the full contract. See the AI Guide.