Firefox 68 for developers
=========================

This article provides information about the changes in Firefox 68 that will affect developers. Firefox 68 was released on July 9, 2019.

Changes for web developers
--------------------------

### Developer tools

#### Browser/web console

* The Web console now shows more information about CSS warnings, including a node list of the DOM elements that used the rule (Firefox bug 1093953).
* You can now filter content in the Web console using regular expressions (Firefox bug 1441079).
* The Browser console now allows you to show or hide messages from the content process by setting or clearing the checkbox labeled *Show Content Messages* (Firefox bug 1260877).

#### JavaScript debugger

* You can now Search in all files in the current project from the debugger by pressing `Shift` + `Ctrl` + `F` (Windows or Linux) or `Shift` + `Cmd` + `F` (macOS) (Firefox bug 1320325).

#### Network monitor

* The Network monitor request list now allows you to block a specific URL (Firefox bug 1151368).
* You can now resend a network request without editing the method, URL, parameters, and headers, using the Resend command on the context menu (Firefox bug 1422014).
* The context menu of the Network monitor Headers tab now allows you to copy all or some of the header information to the clipboard in JSON format (Firefox bug 1442249).

#### Page inspector

* A button has been added to the rules panel of the Page inspector that allows you to toggle the display of any print media queries (Firefox bug 1534984).
* The fonts panel now includes a slider to modify `letter-spacing` (Firefox bug 1536237).
* A warning icon appears next to unsupported CSS properties or rules that have invalid values, to help you understand why certain styles are not being applied (Firefox bug 1306054).

#### Storage inspector

* You can now delete local and session storage entries by selecting the item in the storage inspector and pressing the backspace key (Firefox bug 1522893).

#### Other

* The Accessibility Inspector now includes a new *Check for issues* feature, which will include a number of audit tools to highlight accessibility problems on your web pages. The first available check is *contrast*, for highlighting color contrast problems.
* The preference that controls the visibility of internal extensions (system add-ons and hidden extensions) on the about:debugging page has been changed from `devtools.aboutdebugging.showSystemAddons` to `devtools.aboutdebugging.showHiddenAddons` (Firefox bug 1544372).
* Responsive design mode has been redesigned — the *Device Settings* dialog (device selection menu > *Edit List…*) is now more intuitive and simpler to use (Firefox bug 1487857).

#### Removals

* The "Enable add-on debugging" checkbox has been removed from the about:debugging page (Firefox bug 1544813).
### HTML

* The `<track>` element — represented by `HTMLTrackElement` — now receives a `cuechange` event in addition to the `TextTrack` itself, if the text track is a contained by a media element (Firefox bug 1548731).
* `<link>` elements support the `disabled` attribute again, albeit with different behavior. When `disabled` is set on a `<link>` element along with `rel="stylesheet"`, the referenced stylesheet is not loaded during page load, and will be loaded on demand when the `disabled` attribute is changed to `false` or removed (Firefox bug 1281135).

#### Removals

* `<meta http-equiv="set-cookie">` is no longer supported (Firefox bug 1457503).
### CSS

* CSS Scroll Snapping has been updated to the latest version of the specification (Firefox bug 1312163) and (Firefox bug 1544136), this includes:
    + The `scroll-padding` properties (Firefox bug 1373832)
    + The `scroll-margin` properties (Firefox bug 1373833)
    + `scroll-snap-align` (Firefox bug 1373835)
* The `-webkit-line-clamp` property has been implemented for compatibility with other browsers (Firefox bug 866102).
* Support has been added for the `::marker` pseudo-element (Firefox bug 205202) and animation for `::marker` pseudos (Firefox bug 1538618)
* We changed `currentcolor` to be a computed value (except for the `color` property) (Firefox bug 760345).
* Support has been fixed for the `ch` length unit so it now matches the spec (fallback for no '0' glyph, vertical metrics) (Firefox bug 282126)
* The `counter-set` property has been implemented. (Firefox bug 1518201).
* We now implement list numbering using a built-in "list-item" counter; this fixes list numbering bugs (Firefox bug 288704).
* Selector matching and parsing support has been implemented for `::part()` (Firefox bug 1545430) and (Firefox bug 1545425).
* CSS Transforms are now supported in indirectly rendered things e.g.) `<mask>`, `<marker>`, `<pattern>`, `<clipPath>` (Firefox bug 1323962).
* While we're keeping the prefixed versions of the various gradient properties (`gradient/linear-gradient()`, `gradient/radial-gradient()`, and `gradient/repeating-radial-gradient()` available for compatibility reasons, we have revised how they're parsed so that they're handled much more like the non-prefixed versions. This means that certain existing styles won't work correctly.
 In particular, the complicated syntax taking both an angle and a position will no longer work, and the `to` keyword in the `<side-or-corner>` parameter is not required for the prefixed gradient properties. You are encouraged to use the standard, non-prefixed gradient properties instead, as they're now widely supported (Firefox bug 1547939).

#### Removals

* `scroll-snap-coordinate`, `scroll-snap-destination`, `scroll-snap-type-x` and `scroll-snap-type-y` have been removed.
* The `scroll-snap-type` property has become a longhand, so the old shorthand syntax like `scroll-snap-type:mandatory` will stop working.
### SVG

*No changes.*

### JavaScript

* The new `BigInt` primitive is enabled by default (Firefox bug 1527902).
* String generic methods have been removed (Firefox bug 1222552).
### APIs

#### CSS Object Model (CSSOM)

* The legacy `rules` property and `addRule()` and `removeRule()` methods have been added to the `CSSStyleSheet` interface. These were introduced by Internet Explorer 9 and have never managed to quite be stamped out, so they have been added to improve compatibility with the small percentage of sites that still use them (Firefox bug 1545823).

#### DOM

* The Visual Viewport API has now been enabled by default on Android (Firefox bug 1512813). Adding this API to desktop versions of Firefox is being tracked in Firefox bug 1551302.
* The `Window` feature `noreferrer` is now supported; if specified, the new window's content is loaded without sharing the hostname, IP address, URL, or other identifying information about the host device (Firefox bug 1527287).
* The `decode()` method on `HTMLImageElement` is now implemented. This can be used to trigger loading and decoding of an image prior to adding it to the DOM (Firefox bug 1501794).
* `XMLHttpRequest` has been updated to no longer accept the non-standard `moz-chunked-arraybuffer` value for `responseType`. Code still using it should be updated to use the Fetch API as a stream (Firefox bug 1120171).
* `XMLHttpRequest` now outputs a warning to console if you perform a synchronous request while handling an `unload`, `beforeunload`, or `pagehide` event (Firefox bug 980902).
* The `cookie` property has moved from the `HTMLDocument` interface to the `Document` interface, allowing documents other than HTML to use cookies (Firefox bug 144795).
* The `HTMLElement.focus()` and `SVGElement.focus()` methods now accept an optional object that may contain a boolean `preventScroll` option specifying whether or not to block the browser from scrolling the newly-focused element into view (Firefox bug 1374045).

#### DOM events

* Firefox for Android no longer incorrectly sends a `resize` event until after the first frame is painted; this improves web compatibility with sites that don't expect this event to occur (Firefox bug 1528052).
* The dispatching of events for non-primary mouse buttons has been made to more closely follow the specification; the `click` event is no longer sent when non-primary buttons are clicked, instead using `auxclick`. In addition, `dblclick` no longer fires for non-primary buttons (Firefox bug 1379466).
* The proprietary `mozPressure` property has been deprecated, and will now trigger a warning in the console (Firefox bug 1165211).

#### Media, Web Audio, and WebRTC

* Due to changes in the Google Play store's policies, starting with Firefox 68 for Android, the OpenH264 codec used to handle AVC/H.264 video in WebRTC connections can no longer be downloaded and installed. Therefore, fresh installs of Firefox on Android devices no longer support AVC in WebRTC calls. If you upgrade from earlier versions of Firefox and already have the codec downloaded, it will continue to work. This does *not* affect other platforms. For more details, see this article on SUMO or Firefox bug 1548679.
* WebRTC has been updated to recognize that a `null` candidate passed into the `icecandidate` event handler, indicating the receipt of a candidate, instead indicates that there are no further candidates coming; when this happens the ICE gathering (`iceGatheringState`) state reaches `complete` (Firefox bug 1318167).
* The `RTCRtpReceiver` methods `getContributingSources()` and `getSynchronizationSources()` now support video tracks; previously they only worked on audio (Firefox bug 1534466).
* The Web Audio API `MediaStreamTrackAudioSourceNode` interface is now supported, as is the method `AudioContext.createMediaStreamTrackSource()` (Firefox bug 1324548).
* `RTCDataChannel.negotiated` is now implemented (Firefox bug 1529695).
* The `MediaStreamAudioSourceNode()` constructor has been updated to match the current specification's definition that the "first audio track" in the stream is the track whose ID comes first in lexicographical order (Firefox bug 1324548).
* `getUserMedia()` may no longer be used from a non-secure context; attempting to do so now throws a `NotAllowedError` exception. Secure contexts are those loaded using HTTPS, those located using the `file:///` scheme, and those loaded from `localhost`. For now, if you must, you can re-enable the ability to perform insecure calls to `getUserMedia()` by setting the preference `media.getusermedia.insecure.enabled` to `true` (Firefox bug 1335740).

**Note:** In the future, Firefox will also remove the `navigator.mediaDevices` property on insecure contexts, preventing all access to the `MediaDevices` APIs. **This is already the case in Nightly builds.**

#### Removals

* Removed the non-standard `XMLDocument.load()` method (Firefox bug 332175).
* Removed the non-standard `XMLDocument.async` property (Firefox bug 1328138).
* The `RTCIceServer.credentialType` `token` value has been removed (Firefox bug 1529595).
### HTTP

* The HTTP `Clear-Site-Data` header no longer supports the `executionContexts` directive. This was removed due to problems with interactions between interconnections among different kinds of data at different points in the navigation process and the way the specification is designed. It has been proposed that this directive be removed from the specification for this reason, among others (Firefox bug 1548034).

#### Removals

* The `Content-Security-Policy` directive `require-sri-for` is no longer supported due to concerns about its standardization status. It was previously available only behind a preference, which was off by default (Firefox bug 1386214).
### Security

* Due to CVE-2019-11730: Same-origin policy treats all files in a directory as having the same-origin, changes have been made so that Firefox now treats files in the same directory as being from different origins. This has a number of side-effects on what will work in documents loaded via file:// URLs (see Firefox bug 1558299 for useful background research). For example, workers can no longer be loaded.
### WebDriver conformance (Marionette)

#### Bug fixes

* If `WebDriver:SwitchToWindow` changes the selection to a different window it now waits for its `focus` and `activate` events before returning (Firefox bug 1335085).
* Fixed the `TypeError: this.tabModal is null` failure, which sometimes appeared when interacting with modal dialogs or user prompts (Firefox bug 1538782)

#### Other

* Disabled the feature to force unloading background tabs on low memory conditions, to prevent top-level browser contexts from magically disappearing (Firefox bug 1553748).
* Disabled privileged content processes that caused HTTP authentication dialogs not to appear when navigating to a website after opening a new tab (Firefox bug 1558763).
### Plugins

*No changes.*

Changes for add-on developers
-----------------------------

### API changes

* The `proxy.register()` and `proxy.unregister()` functions have been deprecated and will be removed from Firefox 71 (Firefox bug 1545811).
* A `boolean` flag, `incognito`, has been added to the proxy.RequestDetails. object. When `true`, it indicates that this was a private browsing request (Firefox bug 1545163).
* The webRequest.RequestFilter parameters can include an incognito parameter. If provided, requests that do not match the incognito state (`true` or `false`) will be filtered out (Firefox bug 1548177).
* A `string` value, `cookieStoreId`, representing the cookie store ID of the current context, has been added to the proxy.RequestDetails. object (Firefox bug 1545420).
* When an add-on attempts to add a bookmark folder to the root folder, the resulting error message is now much more intuitive (Firefox bug 1512171).
* The promise returned by `browser.tabs.duplicate()` now resolves immediately, before the tabs are completely loaded (Firefox bug 1394376).
* Support has been added for chrome.storage.managed, allowing web extension settings to be implemented via enterprise policy (Firefox bug 1230802).
* `proxyAuthorization` and `connectionIsolation` in `proxy.onRequest` now apply only to HTTPS proxies (Firefox bug 1549368.
### Manifest changes

*No changes.*

See also
--------

* Hacks release post: Firefox 68: BigInts, Contrast Checks, and the QuantumBar
Older versions
--------------

* Firefox 67 for developers
* Firefox 66 for developers
* Firefox 65 for developers
* Firefox 64 for developers
* Firefox 63 for developers
* Firefox 62 for developers
* Firefox 61 for developers
* Firefox 60 for developers
* Firefox 59 for developers
* Firefox 58 for developers
* Firefox 57 for developers
* Firefox 56 for developers
* Firefox 55 for developers
* Firefox 54 for developers
* Firefox 53 for developers
* Firefox 52 for developers
* Firefox 51 for developers
* Firefox 50 for developers
* Firefox 49 for developers
* Firefox 48 for developers
* Firefox 47 for developers
* Firefox 46 for developers
* Firefox 45 for developers
* Firefox 44 for developers
* Firefox 43 for developers
* Firefox 42 for developers
* Firefox 41 for developers
* Firefox 40 for developers
* Firefox 39 for developers
* Firefox 38 for developers
* Firefox 37 for developers