Chart formats

The texts that a chart draws (data labels, tooltips and axis labels) are described with format strings: a text with {...} tags that are replaced by values. The language is the template language of Highcharts 11. The React engine interprets the subset described in this page in the browser, so a format that only uses that subset gives the same text with ECharts. Other number specifications (anything but .Nf and ,.Nf) write the raw value: check them when you move a chart to the React engine.

<b>{point.name}</b>: {point.percentage:.1f} %

Where formats are used

Place	How to set it	Variables
Data labels	format-data-labels attribute of chart, or dataLabels.format of a series	The point (see below)
Axis labels	label-format attribute of x-axis and y-axis, or labels.format	value
Tooltip, point line	point-format attribute of chart-tooltip, or the pointFormat parameter	The point
Tooltip, header	headerFormat parameter of chart-tooltip	The point
Tooltip, footer	footerFormat parameter of chart-tooltip	The point
Date of the tooltip	date-format attribute of chart-tooltip	The date of the axis

A format that is not set uses the default text of the chart: the name of the series and the value in the tooltip, and the value in the axes.

Syntax

Expressions

An expression is a variable between braces, with an optional specification after a colon:

Expression	Result
{point.y}	The value as it is received, without rounding
{point.y:.2f}	The value with two decimals
{point.y:,.0f}	The value without decimals and with thousands separators
{point.x:%Y-%m-%d}	The x value (a timestamp) as a date
{point.name}	The name of the point

A text between braces that is not a valid expression is kept as text.

Number specifications

.Nf writes the number with N decimals. ,.Nf adds the thousands separator. The decimal point and the separator come from the language of the application (the decimalPoint and thousandsSep entries of src/i18n/charts/charts-<language>.json in the React client). Any other number specification writes the value as it is.

Note: The values are never rounded unless the format (or number-decimals in the tooltip) asks for it. A value of 3.14159265 is drawn as 3.14159265 when there is no specification.

Date specifications

A specification that starts with % formats a timestamp in milliseconds with the local time of the browser:

Code	Meaning	Code	Meaning
%Y	Year (2026)	%H	Hours (00-23)
%y	Year (26)	%M	Minutes
%m	Month number (01-12)	%S	Seconds
%d	Day of the month (01)	%L	Milliseconds
%e	Day of the month (1)	%b	Short month name
%B	Month name	%A	Weekday name
%a	Short weekday name	%%	A percent sign

The names of the months and of the weekdays come from the language file of the chart texts.

Conditions

{#if <condition>}...{else}...{/if} writes one text or the other. The {else} part is optional.

{#if (gt y 0)}{y:,.0f}€{else}{(multiply y -1):,.0f}€{/if}

Helpers

A tag whose first word is a helper calls it with the rest of the words as arguments. The arguments are numbers, variables or other calls between parentheses:

Helper	Result
multiply, divide	Product, quotient
add, subtract	Sum, difference
gt, lt, ge, le	>, <, >=, <=
eq, ne	Equal, not equal

{multiply value 0.001}k
{(subtract y 10):.1f}

The result of a calculation is rounded to remove floating point noise (0.1 + 0.2 is 0.3).

Variables

For data labels and for the lines of the tooltip, the variables describe the point that is drawn:

Variable	Content
point.y, y, value	The value of the point
point.x, x	The x value (a timestamp in a date axis)
point.z, z	The z value of a bubble
point.name, name	The name of the point (the category, or the slice of a pie)
point.key, key	The name of the point, or its x value when it has no name
point.percentage, percentage	The percentage of a slice of a pie
point.color	The color of the point
series.name	The name of the series
series.color	The color of the series
series.userOptions.<name>	An option of the series written as a chart-parameter

In an inverted chart, x and y keep their AWE meaning: x is the x-value of the series and y its y-value.

The labels of an axis have only the variable value.

Data labels and axis labels

Data labels and axis labels are plain text: the HTML tags of the format are removed and the line breaks become spaces.

<chart id="ChrAdvPie" type="pie" enable-data-labels="true"
       format-data-labels="&lt;b&gt;{point.name}&lt;/b&gt;: {point.percentage:.2f} %" ...>

Note: The format goes in an XML attribute, so the characters <, > and & have to be written as <, > and &.

Named formatters

The formatter-function attribute of an axis applies a function by name. There is one:

• formatCurrencyMagnitude: writes a number with the symbol of its magnitude.

Value	Label
300	300
1234	1.23K
100000	100K
12000000	12M

<y-axis formatter-function="formatCurrencyMagnitude"/>

Date axes

The labels of a date axis are chosen by the zoom level. Set the date pattern of each unit with the dateTimeLabelFormats parameter of the axis:

<x-axis type="datetime">
  <chart-parameter type="object" name="dateTimeLabelFormats">
    <chart-parameter type="string" name="month" value="%B %Y"/>
  </chart-parameter>
</x-axis>

Tooltips

The tooltip of a chart shows a header (once), a line for every point and a footer (once). Without formats, the line is the name of the series and the value, and the header is the value of the axis.

The chart-tooltip attributes give the simple formats:

Attribute	Effect
number-decimals	Decimals of the values
prefix	Text before the value
suffix	Text after the value
date-format	Date pattern of the header of a date axis
shared	One tooltip for all the series at the same x value
crosshairs	Guide line of the axes

The suffix of a series (the tooltip.valueSuffix parameter) replaces the one of the tooltip.

HTML tooltips

Use point-format (or the pointFormat, headerFormat and footerFormat parameters) to write your own tooltip. The tags of the template are kept, even without useHTML, like Highcharts does with its basic HTML (b, i, br and span). The values that replace the expressions are escaped, so a value that contains < is shown as text and never becomes markup.

With useHTML set to true the pieces of the tooltip are joined as they are, so a table can be built with the three formats. When a point format is set, the colored marker of the series is not added before its line, because a marker outside a table cell would break the table:

<chart-tooltip shared="false">
  <chart-parameter type="boolean" name="useHTML" value="true"/>
  <chart-parameter type="string" name="headerFormat"
                   value="&lt;table&gt;&lt;tr&gt;&lt;th colspan='2'&gt;{point.key}&lt;/th&gt;&lt;/tr&gt;"/>
  <chart-parameter type="string" name="pointFormat"
                   value="&lt;tr&gt;&lt;td&gt;{series.userOptions.fullname}: &lt;/td&gt;&lt;td&gt;&lt;b&gt;{#if (gt y 0)}{y:,.0f}€{else}{(multiply y -1):,.0f}€{/if}&lt;/b&gt;&lt;/td&gt;&lt;/tr&gt;"/>
  <chart-parameter type="string" name="footerFormat" value="&lt;/table&gt;"/>
</chart-tooltip>

The series of this example hold the text of the line in a custom option, which the format reads as series.userOptions.fullname:

<chart-serie id="men" type="column" x-value="age" y-value="men" label="Men">
  <chart-parameter type="string" name="fullname" value="Average gross salary of men"/>
</chart-serie>