Breaking changes

• #6131 helpers._decimalPlaces is now private

Enhancements

• #6527 Hover styling for dataset in 'dataset' mode
• #6268 Implement dataset.order
• #6509 Make autoSkip aware of major ticks
• #6460 Implemented RTL support for legends and tooltips
• #6490 HTML DOM building
• #6326 Draw the rightmost grid line when offsetGridLines is true
• #6343 Handle reverse support in core.scale
• #6289 Support spanGaps in radar charts
• #6323 Support object values for bar charts
• #6287 Support rotation for pointStyle image
• #6257 Allow specifying labels in time scale options
• #6281 Support boundary filling modes in radialLinear scale
• #6056 Add support for floating bar chart ([start, end])
• #6241 Implement layers (z-index) for layout items
• #5621 Make legend appearance consistent with chart elements
• #5999 Implement per-dataset type (default and per-chart) options
• #6097 Specify time scale min and max in standard manner
• #6141 Legend align option. Thanks @dkichler
• #6128 Make line options scriptable. Thanks @janelledement

Performance

• #6594 Remove a couple calls to helpers.each
• #6247 Remove duplicate scale building
• #6579 Cache resolved data element options
• #6575 Simplify line drawing
• #6508 Add ticks.sampleSize option
• #6354 Perf improvement for ticks.source:'labels'
• #6301 Replace helpers.each with for-loops
• #6304 Refactor core.layout
• #6307 Faster major tick calculation
• #6250 Cache getScaleForId() calls in the line controller
• #6148 Replace helpers.extend

Bug Fixes

• #6249 Bar options should be defined on dataset instead of scale
• #6556 Inject styles into Shadow DOM when inside Shadow DOM
• #6583 Fix unit determination when autoSkip is enabled
• #6581 Return correct index/value id in radar/polarArea
• #6580 Fix logarithmic test to use correct scale
• #6528 Make sure zeroLineIndex is defined
• #6523 Fix right side scale ticks
• #6423 Clamp argument of toExponential between 0 and 20. Thanks @veggiesaurus
• #6328 Fix getValueForPixel in time scale
• #6292 Adjust vertical alignment of tooltip items
• #6321 Update dataset metadata when axisID changes
• #6291 Assign unique scale IDs
• #6288 Fix regression in lineTension
• #6282 Treat null as NaN in radialLinear scale
• #6285 Keep lines on the left and right edges from being cut
• #6269 Apply lineJoin style at the first point in radar charts
• #6280 Fix point label counting in radialLinear scale
• #6279 Treat 0 as a valid point label
• #6265 Utilize tick.major in tickFormatFunction
• #6264 Apply offset regardless of min/max setting
• #6258 Fix ticks generation for vertical time scale
• #6259 Fix determineUnitForFormatting floating point error
• #6115 Fix overlapping auto-generated ticks on time scale
• #6238 Fix tooltip title in radar charts
• #6224 Fix arc size calculation when circumference is under 2*PI
• #6215 Fix arc border with circumference over 2*PI
• #5961 Fix tick label rotation and layout issues
• #6182 Use the appropriate time format for auto tick generation
• #6208 Fill before drawing lines
• #6209 Fix missing tooltip value in radar charts
• #6177 Normalize angle for index in radialLinear scale
• #6102 Fix ticks.minor and ticks.major issues
• #6129 Fix hover animation
• #6120 Improved helpers.almostWhole

Documentation

• #6585 Add a note to the perf documentation about rotation
• #6554 Add link to linear radial axis for radar chart doc
• #6491 Add elements.arc.angle in documentation
• #6466 Fixed incorrect spelling in pie dataset options. Thanks @SeppPenner
• #6435 Add link back to home page from docs
• #6393 Add radar chart config options
• #6293 Correct descriptions on ticks.display and add pointLabels.display
• #6263 Add sample for radar scriptable options
• #6244 Fix data in timeseries sample
• #6186 Typo in doughnut documentation. Thanks @joshuamcewen
• #6132 Make docs consistent for cubicInterpolationMode and fill. Thanks @stockiNail
• #6119 Demonstrate multiple units on timeseries example
• #6139 Documented tooltip alignment options
• #6134 Documented date adapter

Development

• #6507 Improved minimization when calling helpers
• #6497 Reduce indentation
• #6355 Do autoSkip in update
• #6493 Upgrade rollup and plugins
• #6362 Improved code minimization
• #6360 Create helpers.math._factorize
• #6351 Lazily compute label sizes
• #6347 Render charts only once in time scale tests
• #6246 Avoid time related deprecation warnings in tests

Thanks to the maintainers and collaborators for their help to improve and test Chart.js (@nagix, @kurkle, @benmccann, @etimberg and @simonbrunel).