Maplibre

:warning: Breaking changes

- Removed support for paint classes [3643](https://github.com/mapbox/mapbox-gl-js/pull/3643). Instead, use runtime styling APIs or `Map#setStyle`.
- Reverted the `canvas` source `contextType` option added in 0.40.0 [5449](https://github.com/mapbox/mapbox-gl-js/pull/5449)

:bug: Bug fixes

- Clip raster tiles to avoid tile overlap [5105](https://github.com/mapbox/mapbox-gl-js/pull/5105)
- Guard for offset edgecase in flyTo [5331](https://github.com/mapbox/mapbox-gl-js/pull/5331)
- Ensure the map is updated after the sprite loads [5367](https://github.com/mapbox/mapbox-gl-js/pull/5367)
- Limit animation duration on flyTo with maxDuration option [5349](https://github.com/mapbox/mapbox-gl-js/pull/5349)
- Make double-tapping on make zoom in by a factor of 2 on iOS [5274](https://github.com/mapbox/mapbox-gl-js/pull/5274)
- Fix rendering error with translucent raster tiles [5380](https://github.com/mapbox/mapbox-gl-js/pull/5380)
- Error if invalid 'before' argument is passed to MapaddLayer [5401](https://github.com/mapbox/mapbox-gl-js/pull/5401)
- Revert CanvasSource intermediary image buffer fix [5449](https://github.com/mapbox/mapbox-gl-js/pull/5449)

:sparkles: Features and improvements

- Use setData operation when diffing geojson sources [5332](https://github.com/mapbox/mapbox-gl-js/pull/5332)
- Return early from draw calls on layers where opacity=0 [5429](https://github.com/mapbox/mapbox-gl-js/pull/5429)
- A [heatmap](https://www.mapbox.com/mapbox-gl-js/example/heatmap-layer/) layer type is now available. This layer type allows you to visualize and explore massive datasets of points, reflecting the shape and density of data well while also looking beautiful. See [the blog post](https://blog.mapbox.com/sneak-peek-at-heatmaps-in-mapbox-gl-73b41d4b16ae) for further details.
- The value of a style property or filter can now be an [expression](https://www.mapbox.com/mapbox-gl-js/style-spec/#expressions). Expressions are a way of doing data-driven and zoom-driven styling that provides more flexibility and control, and unifies property and filter syntax.

Previously, data-driven and zoom-driven styling relied on stop functions: you specify a feature property and a set of input-output pairs that essentially define a “scale” for how the style should be calculated based on the feature property. For example, the following would set circle colors on a green-to-red scale based on the value of `feature.properties.population`:


"circle-color": {
"property": "population",
"stops": [
[0, "green"],
[1000000, "red"]
]
}


This approach is powerful, but we’ve seen a number of use cases that stop functions don't satisfy. Expressions provide the flexibility to address use cases like these:

**Multiple feature properties**
Using more than one feature property to calculate a given style property. E.g., styling land polygon colors based on both `feature.properties.land_use_category` and `feature.properties.elevation`.

**Arithmetic**
For some use cases it’s necessary to do some arithmetic on the input data. One example is sizing circles to represent quantitative data. Since a circle’s visual size on the screen is really its area (and A=πr^2), the right way to scale `circle-radius` is `square_root(feature.properties.input_data_value)`. Another example is unit conversions: feature data may include properties that are in some particular unit. Displaying such data in units appropriate to, say, a user’s preference or location, requires being able to do simple arithmetic (multiplication, division) on whatever value is in the data.

**Conditional logic**
This is a big one: basic if-then logic, for example to decide exactly what text to display for a label based on which properties are available in the feature or even the length of the name. A key example of this is properly supporting bilingual labels, where we have to decide whether to show local + English, local-only, or English-only, based on the data that’s available for each feature.

**String manipulation**
More dynamic control over label text with things like uppercase/lowercase/title case transforms, localized number formatting, etc. Without this functionality, crafting and iterating on label content entails a large data-prep burden.

**Filters**
Style layer filters had similar limitations. Moreover, they use a different syntax, even though their job is very similar to that of data-driven styling functions: filters say, “here’s how to look at a feature and decide whether to draw it,” and data-driven style functions say, “here’s how to look at a feature and decide how to size/color/place it.” Expressions provide a unified syntax for defining parts of a style that need to be calculated dynamically from feature data.

For information on the syntax and behavior of expressions, please see [the documentation](https://www.mapbox.com/mapbox-gl-js/style-spec/#expressions).

:wrench: Development workflow improvements

- Made the performance benchmarking runner more informative and statistically robust

:bug: Bug fixes

- Fix bug causing flicker when zooming in on overzoomed tiles [5295](https://github.com/mapbox/mapbox-gl-js/pull/5295)
- Remove erroneous call to TileredoPlacement for zoom-only or low pitch camera changes [5284](https://github.com/mapbox/mapbox-gl-js/pull/5284)
- Fix bug where `CanvasSource` coordinates were flipped and improve performance for non-animated `CanvasSource`s [5303](https://github.com/mapbox/mapbox-gl-js/pull/5303)
- Fix bug causing map not to render on some cases on Internet Explorer 11 [5321](https://github.com/mapbox/mapbox-gl-js/pull/5321)
- Remove upper limit on `fill-extrusion-height` property [5320](https://github.com/mapbox/mapbox-gl-js/pull/5320)

:warning: Breaking changes

- `MapaddImage` now requires the image as an `HTMLImageElement`, `ImageData`, or object with `width`, `height`, and
`data` properties with the same format as `ImageData`. It no longer accepts a raw `ArrayBufferView` in the second
argument and `width` and `height` options in the third argument.
- `canvas` sources now require a `contextType` option specifying the drawing context associated with the source canvas. [5155](https://github.com/mapbox/mapbox-gl-js/pull/5155)

:sparkles: Features and improvements

- Correct rendering for multiple `fill-extrusion` layers on the same map [5101](https://github.com/mapbox/mapbox-gl-js/pull/5101)
- Add an `icon-anchor` property to symbol layers [5183](https://github.com/mapbox/mapbox-gl-js/pull/5183)
- Add a per-map `transformRequest` option, allowing users to provide a callback that transforms resource request URLs [5021](https://github.com/mapbox/mapbox-gl-js/pull/5021)
- Add data-driven styling support for
- `text-max-width` [5067](https://github.com/mapbox/mapbox-gl-js/pull/5067)
- `text-letter-spacing` [5071](https://github.com/mapbox/mapbox-gl-js/pull/5071)
- `line-join` [5020](https://github.com/mapbox/mapbox-gl-js/pull/5020)
- Add support for SDF icons in `MapaddImage()` [5181](https://github.com/mapbox/mapbox-gl-js/pull/5181)
- Added nautical miles unit to ScaleControl [5238](https://github.com/mapbox/mapbox-gl-js/pull/5238) (h/t [fmairesse](https://github.com/fmairesse)))
- Eliminate the map-wide limit on the number of glyphs and sprites that may be used in a style [141](https://github.com/mapbox/mapbox-gl-js/issues/141). (Fixed by [#5190](https://github.com/mapbox/mapbox-gl-js/pull/5190), see also [mapbox-gl-native[#9213](https://github.com/mapbox/mapbox-gl-js/issues/9213)](https://github.com/mapbox/mapbox-gl-native/pull/9213)
- Numerous performance optimizations (including [5108](https://github.com/mapbox/mapbox-gl-js/pull/5108) h/t [pirxpilot](https://github.com/pirxpilot)))

:bug: Bug fixes

- Add missing documentation for mouseenter, mouseover, mouseleave events [4772](https://github.com/mapbox/mapbox-gl-js/issues/4772)
- Add missing documentation for `MarkergetElement()` method [5242](https://github.com/mapbox/mapbox-gl-js/pull/5242)
- Fix bug wherein removing canvas source with animate=true leaves map in render loop [5097](https://github.com/mapbox/mapbox-gl-js/issues/5097)
- Fix fullscreen detection on Firefox [5272](https://github.com/mapbox/mapbox-gl-js/pull/5272)
- Fix z-fighting on overlapping fills within the same layer [3320](https://github.com/mapbox/mapbox-gl-js/issues/3320)
- Fix handling of fractional values for `layer.minzoom` [2929](https://github.com/mapbox/mapbox-gl-js/issues/2929)
- Clarify coordinate ordering in documentation for `center` option [5042](https://github.com/mapbox/mapbox-gl-js/pull/5042) (h/t [karthikb351](https://github.com/karthikb351)))
- Fix output of stop functions where two stops have the same input value [5020](https://github.com/mapbox/mapbox-gl-js/pull/5020) (h/t [edpop](https://github.com/edpop))
- Fix bug wherein using `MapaddLayer()` with an inline source would mutate its input [4040](https://github.com/mapbox/mapbox-gl-js/issues/4040)
- Fix invalid css keyframes selector [5075](https://github.com/mapbox/mapbox-gl-js/pull/5075) (h/t [aar0nr](https://github.com/aar0nr)))
- Fix GPU-specific bug wherein canvas sources caused an error [4262](https://github.com/mapbox/mapbox-gl-js/issues/4262)
- Fix a race condition in symbol layer handling that caused sporadic uncaught errors [5185](https://github.com/mapbox/mapbox-gl-js/pull/5185)
- Fix bug causing line labels to render incorrectly on overzoomed tiles [5120](https://github.com/mapbox/mapbox-gl-js/pull/5120)
- Fix bug wherein `NavigationControl` triggered mouse events unexpectedly [5148](https://github.com/mapbox/mapbox-gl-js/issues/5148)
- Fix bug wherein clicking on the `NavigationControl` compass caused an error in IE 11 [4784](https://github.com/mapbox/mapbox-gl-js/issues/4784)
- Remove dependency on GPL-3-licensed `fast-stable-stringify` module [5152](https://github.com/mapbox/mapbox-gl-js/issues/5152)
- Fix bug wherein layer-specific an event listener produced an error after its target layer was removed from the map [5145](https://github.com/mapbox/mapbox-gl-js/issues/5145)
- Fix `MarkertogglePopup()` failing to return the marker instance [5116](https://github.com/mapbox/mapbox-gl-js/issues/5116)
- Fix bug wherein a marker's position failed to adapt to the marker element's size changing [5133](https://github.com/mapbox/mapbox-gl-js/issues/5133)
- Fix rendering bug affecting Broadcom GPUs [5073](https://github.com/mapbox/mapbox-gl-js/pull/5073)

:wrench: Development workflow improvements

- Add (and now require) Flow type annotations throughout the majority of the codebase.
- Migrate to CircleCI 2.0 [4939](https://github.com/mapbox/mapbox-gl-js/pull/4939)

:bug: Bug fixes

- Fix packaging issue in 0.39.0 [5025](https://github.com/mapbox/mapbox-gl-js/issues/5025)
- Correctly evaluate enum-based identity functions [5023](https://github.com/mapbox/mapbox-gl-js/issues/5023)

:warning: Breaking changes

- `GeolocateControl` breaking changes [4479](https://github.com/mapbox/mapbox-gl-js/pull/4479)
- The option `watchPosition` has been replaced with `trackUserLocation`
- The camera operation has changed from `jumpTo` (not animated) to `fitBounds` (animated). An effect of this is the map pitch is no longer reset, although the bearing is still reset to 0.
- The accuracy of the geolocation provided by the device is used to set the view (previously it was fixed at zoom level 17). The `maxZoom` can be controlled via the new `fitBoundsOptions` option (defaults to 15).
- Anchor `Marker`s at their center by default [5019](https://github.com/mapbox/mapbox-gl-js/issues/5019) [andrewharvey](https://github.com/andrewharvey)
- Increase `significantRotateThreshold` for the `TouchZoomRotateHandler` [4971](https://github.com/mapbox/mapbox-gl-js/pull/4971), [dagjomar](https://github.com/dagjomar)

:sparkles: Features and improvements

- Improve performance of updating GeoJSON sources [4069](https://github.com/mapbox/mapbox-gl-js/pull/4069), [ezheidtmann](https://github.com/ezheidtmann)
- Improve rendering speed of extrusion layers [4818](https://github.com/mapbox/mapbox-gl-js/pull/4818)
- Improve line label legibility in pitched views [4781](https://github.com/mapbox/mapbox-gl-js/pull/4781)
- Improve line label legibility on curved lines [4853](https://github.com/mapbox/mapbox-gl-js/pull/4853)
- Add user location tracking capability to `GeolocateControl` [4479](https://github.com/mapbox/mapbox-gl-js/pull/4479), [andrewharvey](https://github.com/andrewharvey)
- New option `showUserLocation` to draw a "dot" as a `Marker` on the map at the user's location
- An active lock and background state are introduced with `trackUserLocation`. When in active lock the camera will update to follow the user location, however if the camera is changed by the API or UI then the control will enter the background state where it won't update the camera to follow the user location.
- New option `fitBoundsOptions` to control the camera operation
- New `trackuserlocationstart` and `trackuserlocationend` events
- New `LngLat.toBounds` method to extend a point location by a given radius to a `LngLatBounds` object
- Include main CSS file in `package.json` [4809](https://github.com/mapbox/mapbox-gl-js/pull/4809), [tomscholz](https://github.com/tomscholz)
- Add property function (data-driven styling) support for `line-width` [4773](https://github.com/mapbox/mapbox-gl-js/pull/4773)
- Add property function (data-driven styling) support for `text-anchor` [4997](https://github.com/mapbox/mapbox-gl-js/pull/4997)
- Add property function (data-driven styling) support for `text-justify` [5000](https://github.com/mapbox/mapbox-gl-js/pull/5000)
- Add `maxTileCacheSize` option [4778](https://github.com/mapbox/mapbox-gl-js/pull/4778), [jczaplew](https://github.com/jczaplew)
- Add new `icon-pitch-alignment` and `circle-pitch-alignment` properties [4869](https://github.com/mapbox/mapbox-gl-js/pull/4869) [#4871](https://github.com/mapbox/mapbox-gl-js/pull/4871)
- Add `MapgetMaxBounds` method [4890](https://github.com/mapbox/mapbox-gl-js/pull/4890), [andrewharvey](https://github.com/andrewharvey) [lamuertepeluda](https://github.com/lamuertepeluda)
- Add option (`localIdeographFontFamily`) to use TinySDF to avoid loading expensive CJK glyphs [4895](https://github.com/mapbox/mapbox-gl-js/pull/4895)
- If `config.API_URL` includes a path prepend it to the request URL [4995](https://github.com/mapbox/mapbox-gl-js/pull/4995)
- Bump `supercluster` version to expose `cluster_id` property on clustered sources [5002](https://github.com/mapbox/mapbox-gl-js/pull/5002)

:bug: Bug fixes

- Do not display `FullscreenControl` on unsupported devices [4838](https://github.com/mapbox/mapbox-gl-js/pull/4838), [stepankuzmin](https://github.com/stepankuzmin)
- Fix yarn build on Windows machines [4887](https://github.com/mapbox/mapbox-gl-js/pull/4887)
- Prevent potential memory leaks by dispatching `loadData` to the same worker every time [4877](https://github.com/mapbox/mapbox-gl-js/pull/4877)
- Fix bug preventing the rtlTextPlugin from loading before the initial style `load` [4870](https://github.com/mapbox/mapbox-gl-js/pull/4870)
- Fix bug causing runtime-stying to not take effect in some situations [4893](https://github.com/mapbox/mapbox-gl-js/pull/4893)
- Prevent requests of vertical glyphs for labels that can't be verticalized [4720](https://github.com/mapbox/mapbox-gl-js/issues/4720)
- Fix character detection for Zanabazar Square [4940](https://github.com/mapbox/mapbox-gl-js/pull/4940)
- Fix `LogoControl` logic to update correctly, and hide the `<div>` instead of removing it from the DOM when it is not needed [4842](https://github.com/mapbox/mapbox-gl-js/pull/4842)
- Fix `GeoJSONSourceserialize` to include all options
- Fix error handling in `GlyphSourcegetSimpleGlyphs`[4992](https://github.com/mapbox/mapbox-gl-js/pull/4992)
- Fix bug causing `setStyle` to reload raster tiles [4852](https://github.com/mapbox/mapbox-gl-js/pull/4852)
- Fix bug causing symbol layers not to render on devices with non-integer device pixel ratios [4989](https://github.com/mapbox/mapbox-gl-js/pull/4989)
- Fix bug where `MapqueryRenderedFeatures` would error when returning no results [4993](https://github.com/mapbox/mapbox-gl-js/pull/4993)
- Fix bug where `MapareTilesLoaded` would always be false on `sourcedata` events for reloading tiles [4987](https://github.com/mapbox/mapbox-gl-js/pull/4987)
- Fix bug causing categorical property functions to error on non-ascending order stops [4996](https://github.com/mapbox/mapbox-gl-js/pull/4996)

:hammer_and_wrench: Development workflow changes

- Use flow to type much of the code base [4629](https://github.com/mapbox/mapbox-gl-js/pull/4629) [#4903](https://github.com/mapbox/mapbox-gl-js/pull/4903) [#4909](https://github.com/mapbox/mapbox-gl-js/pull/4909) [#4910](https://github.com/mapbox/mapbox-gl-js/pull/4910) [#4911](https://github.com/mapbox/mapbox-gl-js/pull/4911) [#4913](https://github.com/mapbox/mapbox-gl-js/pull/4913) [#4915](https://github.com/mapbox/mapbox-gl-js/pull/4915) [#4918](https://github.com/mapbox/mapbox-gl-js/pull/4918) [#4932](https://github.com/mapbox/mapbox-gl-js/pull/4932) [#4933](https://github.com/mapbox/mapbox-gl-js/pull/4933) [#4948](https://github.com/mapbox/mapbox-gl-js/pull/4948) [#4949](https://github.com/mapbox/mapbox-gl-js/pull/4949) [#4955](https://github.com/mapbox/mapbox-gl-js/pull/4955) [#4966](https://github.com/mapbox/mapbox-gl-js/pull/4966) [#4967](https://github.com/mapbox/mapbox-gl-js/pull/4967) [#4973](https://github.com/mapbox/mapbox-gl-js/pull/4973) :muscle: [jfirebaugh](https://github.com/jfirebaugh) [vicapow](https://github.com/vicapow)
- Use style specification to generate flow type [4958](https://github.com/mapbox/mapbox-gl-js/pull/4958)
- Explicitly list which files to publish in `package.json` [4819](https://github.com/mapbox/mapbox-gl-js/pull/4819) [tomscholz](https://github.com/tomscholz)
- Move render test ignores to a separate file [4977](https://github.com/mapbox/mapbox-gl-js/pull/4977)
- Add code of conduct [5015](https://github.com/mapbox/mapbox-gl-js/pull/5015) :sparkling_heart:

New features :sparkles:

- Attenuate label size scaling with distance, improving readability of pitched maps [4547](https://github.com/mapbox/mapbox-gl-js/pull/4547)

Bug fixes :beetle:

- Skip rendering for patterned layers when pattern is missing [4687](https://github.com/mapbox/mapbox-gl-js/pull/4687)
- Fix bug with map failing to rerender after `webglcontextlost` event [4725](https://github.com/mapbox/mapbox-gl-js/pull/4725) [cdawi](https://github.com/cdawi)
- Clamp zoom level in `flyTo` to within the map's specified min- and maxzoom to prevent undefined behavior [4726](https://github.com/mapbox/mapbox-gl-js/pull/4726) [](https://github.com/) IvanSanchez
- Fix wordmark rendering in IE [4741](https://github.com/mapbox/mapbox-gl-js/pull/4741)
- Fix slight pixelwise symbol rendering bugs caused by incorrect sprite calculations [4737](https://github.com/mapbox/mapbox-gl-js/pull/4737)
- Prevent exceptions thrown by certain `flyTo` calls [4761](https://github.com/mapbox/mapbox-gl-js/pull/4761)
- Fix "Improve this map" link [4685](https://github.com/mapbox/mapbox-gl-js/pull/4685)
- Tweak `queryRenderedSymbols` logic to better account for pitch scaling [4792](https://github.com/mapbox/mapbox-gl-js/pull/4792)
- Fix for symbol layers sometimes failing to render, most frequently in Safari [4795](https://github.com/mapbox/mapbox-gl-js/pull/4795)
- Apply `text-keep-upright` after `text-offset` to keep labels upright when intended [4779](https://github.com/mapbox/mapbox-gl-js/pull/4779) **[Potentially breaking :warning: but considered a bugfix]**
- Prevent exceptions thrown by empty GeoJSON tiles [4803](https://github.com/mapbox/mapbox-gl-js/pull/4803)

Accessibility improvements :sound:

- Add `aria-label` to popup close button [4799](https://github.com/mapbox/mapbox-gl-js/pull/4799) [andrewharvey](https://github.com/andrewharvey)

Development workflow + testing improvements :wrench:

- Fix equality assertion bug in tests [4731](https://github.com/mapbox/mapbox-gl-js/pull/4731) [IvanSanchez](https://github.com/IvanSanchez)
- Benchmark results page improvements [4746](https://github.com/mapbox/mapbox-gl-js/pull/4746)
- Require node version >=6.4.0, enabling the use of more ES6 features [4752](https://github.com/mapbox/mapbox-gl-js/pull/4752)
- Document missing `pitchWithRotate` option [4800](https://github.com/mapbox/mapbox-gl-js/pull/4800) [simast](https://github.com/simast)
- Move Github-specific Markdown files into subdirectory [4806](https://github.com/mapbox/mapbox-gl-js/pull/4806) [tomscholz](https://github.com/tomscholz)