Axes

Axes are an integral part of a chart. They are used to determine how data maps to a pixel value on the chart. In a cartesian chart, there is 1 or more X axis and 1 or more Y axis to map points onto the 2 dimensional canvas. These axes are know as 'cartesian axes'.

In a radial chart, such as a radar chart or a polar area chart, there is a single axis that maps points in the angular and radial directions. These are known as 'radial axes'.

Scales in Chart.js >v2.0 are significantly more powerful, but also different than those of v1.0.

  • Multiple X & Y axes are supported.
  • A built-in label auto-skip feature detects would-be overlapping ticks and labels and removes every nth label to keep things displaying normally.
  • Scale titles are supported.
  • New scale types can be extended without writing an entirely new chart type.

Common Configuration

The following properties are common to all axes provided by Chart.js.

Name Type Default Description
display Boolean true If set to false the axis is hidden from view. Overrides gridLines.display, scaleLabel.display, and ticks.display.
callbacks Object Callback functions to hook into the axis lifecycle. more...
weight Number 0 The weight used to sort the axis. Higher weights are further away from the chart area.

Callbacks

There are a number of config callbacks that can be used to change parameters in the scale at different points in the update process.

Name Arguments Description
beforeUpdate axis Callback called before the update process starts.
beforeSetDimensions axis Callback that runs before dimensions are set.
afterSetDimensions axis Callback that runs after dimensions are set.
beforeDataLimits axis Callback that runs before data limits are determined.
afterDataLimits axis Callback that runs after data limits are determined.
beforeBuildTicks axis Callback that runs before ticks are created.
afterBuildTicks axis Callback that runs after ticks are created. Useful for filtering ticks.
beforeTickToLabelConversion axis Callback that runs before ticks are converted into strings.
afterTickToLabelConversion axis Callback that runs after ticks are converted into strings.
beforeCalculateTickRotation axis Callback that runs before tick rotation is determined.
afterCalculateTickRotation axis Callback that runs after tick rotation is determined.
beforeFit axis Callback that runs before the scale fits to the canvas.
afterFit axis Callback that runs after the scale fits to the canvas.
afterUpdate axis Callback that runs at the end of the update process.

Updating Axis Defaults

The default configuration for a scale can be easily changed using the scale service. All you need to do is to pass in a partial configuration that will be merged with the current scale default configuration to form the new default.

For example, to set the minimum value of 0 for all linear scales, you would do the following. Any linear scales created after this time would now have a minimum of 0.

Chart.scaleService.updateScaleDefaults('linear', {
    ticks: {
        min: 0
    }
});

Creating New Axes

To create a new axis, see the developer docs.

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