JavaScript Charts: Tooltips
There are four ways of enabling the tooltips in AG Charts by using:
- default tooltips
- custom styled tooltips via CSS classes
- custom title / content via a renderer function
- completely custom template and markup via a renderer function
Default Tooltip
The default chart tooltip has the following template:
<div class="ag-chart-tooltip">
<div class="ag-chart-tooltip-title"></div>
<div class="ag-chart-tooltip-content"></div>
</div>
The title element may or may not exist but the content element is always present. In the screenshots below the content element of both tooltips contains Jun: 50.00
:


To make the tooltip title visible you need to specify the series' yName
, or labelName
in the case of 'pie'
series. These configs supply the keys used to fetch the display names, because the keys themselves may not be presentable or descriptive.
Example: Default Tooltip
In the sample data below the value1
key is not descriptive, while hats_made
is not very presentable:
data: [
{
month: "Jun",
value1: 50,
hats_made: 40,
},
// ...
]
Notice that when we set the yName
of the 'column'
series:
- The tooltip title is visible when
yName
config is set, and hidden when theyName
is reset. - The
yName
changes are reflected in the legend as well. - The legend will use the
yKey
when theyName
is not set. The tooltip however will only have a title if theyName
(ortitle
) is set.
Also note that for numeric values the tooltips show two digits after the decimal point by default.
Styling the Default Tooltip
The default tooltip already uses ag-chart-tooltip
, ag-chart-tooltip-title
and ag-chart-tooltip-content
CSS classes, but these classes are not meant to be used directly to add custom CSS rules to, unless you want to change the styling of all the tooltips in your app. Instead, users of the charting library should provide their own tooltip class name via the chart.tooltip.class
config. This class name will be added to the class list of the tooltip element for only that particular chart instance.
For example, if we wanted to set the tooltip's content background-color
to gold
, we'd add a custom class name to our chart in the code:
chart.tooltip.class = "my-tooltip"
And then in the CSS:
.my-tooltip .ag-chart-tooltip-content {
background-color: gold;
}
This limits the styling changes to this chart instance alone (or instances that use the same tooltip class). We could style the title element and the container element in the same manner.
Note that your styles don't override the default tooltip styles but complement them.
Example: Tooltip Styling
In this example we show how to change the content's background color and the color of the tooltip's arrow to gold.
Modifying Content / Title
To control what goes into the title and content divs of the tooltip one can set up a tooltip renderer function (one per series) that receives values associated with the highlighted data point and returns an object with the title
and content
fields containing plain text or inner HTML that goes into the corresponding divs:
tooltip: {
renderer?: (params: AgSeriesTooltipRendererParams) => AgTooltipRendererResult;
}
interface AgTooltipRendererResult {
title?: string;
content?: string;
}
The actual type of the params
object passed into the tooltip renderer will depend on the series type being used. See the tooltips API Reference renderer
function examples.
Let's say we wanted to remove the digits after the decimal point from the values shown in tooltips. We could use the following tooltip renderer to achieve that:
tooltip: {
renderer: function (params) {
return {
content: params.yValue.toFixed(0),
title: params.xValue
};
}
}
The example below demonstrates the above tooltip renderer in action:
Using Custom Tooltips
Instead of having the tooltip renderer return an object with title and content strings to be used in the default tooltip template, you can return a string with completely custom markup that will override not just the title and content but the template as well.
Let's say we wanted to remove the digits after the decimal point from the values shown in tooltips (by default the tooltips show two digits after the decimal point for numeric values). We could use the following tooltip renderer to achieve that:
series: [
{
type: "column",
tooltip: {
renderer: function (params) {
return `
<div class="ag-chart-tooltip-title" style="background-color: ${params.color}">
${params.xValue}
</div>
<div class="ag-chart-tooltip-content">
${params.yValue}
</div>`
},
},
},
]
The tooltip renderer function receives the params
object as a single parameter. Inside that object you get the xValue
and yValue
for the highlighted data point as well as the reference to the raw datum
element from the chart.data
or series.data
array. You can then process the raw values however you like before using them as a part of the returned HTML string.
Different series types get different tooltip renderer parameters. You can find out which parameters are supported by which series using the API reference below.
The effect of applying the tooltip renderer from the snippet above can be seen in the example below.
Example: Tooltip Renderer
Notice that the tooltip renderer in the example below:
- Returns two
div
elements, one for the tooltip's title and another for its content. - The value of the title comes from
params.xValue
which is the name of the month. - The title element gets its background color from the
params
object. The provided color matches the color of the series. - The
'Sweaters Made'
value comes from theparams.yValue
, which we then stringify as an integer viatoFixed(0)
. - We use the default class names on the returned
div
elements, so that our tooltip gets the default styling. You could however add your own classes to the class list, or replace the default CSS classes with your own. The structure of the returned DOM is also up to you, we are just following the convention for this example.
Tooltip Range
By default, the tooltip of the nearest node is visible when the cursor is on the chart. However, this behaviour can be changed with the chart.tooltip.range
property.
Example: Tooltip range variations
The example below shows the three types of interaction range:
'nearest'
(default) will show the tooltip of the nearest node anywhere on the chart'exact'
will show the tooltip if the user hovers over a node- given a number the tooltip will show if the cursor is within that distance in pixels of a node
API Reference
Bar/Column Tooltips
Properties available on the AgBarSeriesTooltip
interface.
Area Tooltips
Properties available on the AgAreaSeriesTooltip
interface.
Line Tooltips
Properties available on the AgLineSeriesTooltip
interface.
Scatter/Bubble Tooltips
Properties available on the AgScatterSeriesTooltip
interface.
Pie/Doughnut Tooltips
Properties available on the AgPieSeriesTooltip
interface.
Histogram Tooltips
Properties available on the AgHistogramSeriesTooltip
interface.
Next Up
Continue to the next section to learn about axes.
- Tooltips
- Default Tooltip
- Example: Default Tooltip
- Styling the Default Tooltip
- Example: Tooltip Styling
- Modifying Content / Title
- Using Custom Tooltips
- Example: Tooltip Renderer
- Tooltip Range
- Example: Tooltip range variations
- API Reference
- Bar/Column Tooltips
- Area Tooltips
- Line Tooltips
- Scatter/Bubble Tooltips
- Pie/Doughnut Tooltips
- Histogram Tooltips
- Next Up