JavaScript ChartsTooltips

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:

No Title

With Title

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 the yName is reset.
• The yName changes are reflected in the legend as well.
• The legend will use the yKey when the yName is not set. The tooltip however will only have a title if the yName (or title) is set.

Also note that for numeric values the tooltips show two digits after the decimal point by default.

Tooltip Position

The tooltip position can be modified using the tooltip.position.type property.

tooltip.position.type can be one of the following:

• node - Anchors the tooltip to the highlighted node
• pointer - Anchors the tooltip to the mouse pointer

For series with markers, such as line, area, and scatter, where each data point is represented by a marker, the default tooltip position.type is node. This means that the tooltip will be positioned above the highlighted marker node.

For series without markers, such as bar,column, histogram, treemap and pie, where each data point is represented by a fixed shape, for example a rectangle or a pie sector, the default tooltip position.type is pointer. This means that the tooltip will follow the mouse pointer as it moves over the shapes.

The xOffset and yOffset properties in tooltip.position options define the distance in pixels from the tooltip to the anchor point:

tooltip: {
    position: {
        type: 'pointer',
        xOffset: 80, // positions tooltip 80px to the right of the mouse cursor
        yOffset: 80, // positions tooltip 80px down from the start of the mouse cursor
    }
}

Example: Tooltip Position

In this example we show how to change the tooltip's default position. Note that:

• Instead of the tooltip being anchored to the highlighted marker node, it is anchored 80 pixels to the left and below the mouse pointer.
• By default, when tooltip.position.xOffset or tooltip.position.yOffset are configured, the tooltip arrow is removed.

Tooltip Arrow

The chart tooltip shows an arrow below it to indicate its exact point of origin when it's unconstrained by the container and has no position offset supplied.

Set tooltip.showArrow to true to always show the arrow, and set it to false to remove the arrow.

tooltip: {
  showArrow: false
}

This can be useful if the tooltip's position has been modified and the arrow is no longer needed.

Example: Removing the Tooltip Arrow

In this example, the button above the chart can be used to show or hide the tooltip arrow.

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.

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 the params.yValue, which we then stringify as an integer via toFixed(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

Interaction with Tooltips

By default, you can not hover over a tooltip or select its text. Set the series[].tooltip.interaction.enabled flag to true to enable selecting the text and clicking links within the tooltip.

Example: Interaction with Tooltips

API Reference

All Tooltips

Bar/Column Tooltips

Area Tooltips

Line Tooltips

Scatter/Bubble Tooltips

Pie/Doughnut Tooltips

Histogram Tooltips