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Web Compatibility issues change over time. Bugs that were common in 2005 are not often seen in the present. This list represents the most common issues currently being discovered by the webcompat community and will be updated as these change in the future.


Current Popular Issues

(This needs to be adjusted).

Bugzilla WebCompat Core Bug

Full Query
ID Summary Priority Status
91370 Implement setting cssText on various CSSRule implementations P3 NEW
102695 [EVENTTARG]Treat some transparent elements as "transparent to events" P3 NEW
129432 'onkeypress', 'onkeydown', onkeyup' not working on FORM,LEGEND,OPTGROUP,OPTION -- NEW
137687 Computed CSSDeclarations need to implement GetCssText P3 NEW
162369 scrolling to named anchor doesn't consider areas covered by fixed positioned elements -- NEW
184051 Fire middle/right-click events at content and remove click hack P3 NEW
307866 min-width/min-height/max-width/max-height does not work for table elements -- NEW
406488 Copy highlighted text to clipboard ignores non-inlined CSS styling when pasting as rich text (to HTML editors, MS Word, Excel, Outlook etc.) -- NEW
477157 Borders scale differently than other sizes (e.g. margins, content-sizes, backgrounds), under full-page-zoom or HiDPI -- NEW
568313 Impossible to make <button>s draggable -- NEW
608812 Outer <SVG> element should snap to pixel coordinates -- NEW
612118 SVGLocatable.getBBox() fails unless the SVG element it is applied to is attached and rendered -- NEW
616436 [meta] Implement column-span (from CSS3 multicolumn) P2 NEW
662496 autofocus not work when window.onload P5 UNCONFIRMED
688556 Background of cell paints over border when borders are collapsed and tbody, row, or cell is relatively positioned P3 NEW
688990 Implement "Pinch to zoom" like Safari (and not like it used to be in Firefox) P3 NEW
695868 Unable to set document.body.innerHTML of IFrame P3 NEW
697151 Synchronous XMLHttpRequest (XHR) does not block readyState events for async XHR P5 NEW
836897 Implement the WebMIDI API P3 NEW
876985 flex items with flex-basis:auto and width:auto should get sized as max-content -- ASSIGNED
997189 Absolutely positioned inline-block (or inline) element with floating nextSibling and auto "left" is positioned to the right of the float -- NEW
1005603 When possible, <input type=number> should preserve the formatting of the 'value' attribute or any string assigned to input.value P2 ASSIGNED
1034018 outline: auto is not applied in the same way as it is on blink P3 NEW
1039871 Add support to HTML media element for determining the mimetype of a loaded media file -- NEW
1043118 Do not select trailing spaces on double clicking. P3 NEW
1092007 For flex items in a vertical flex container, only treat heights as definite (for resolving % heights on children) if the flex-basis (or flex container's height) is also definite -- NEW
1099204 Textarea text scrolls under padding instead of over -- REOPENED
1118710 SVG mask animation is not working P2 NEW
1136312 update to match flexbox spec language on "min-width:auto" & items with intrinsic aspect ratios -- NEW
1174452 Copying text with the style "white-space: pre;" does not preserve white space (spaces, tabs, newlines) (Pretty old bug 116083 has come back after change by bug 1151873) P3 NEW
1183449 SVG element with CSS transform and stroke renders at wrong position, probably because of rounding -- NEW
1199665 Consider making <input type=number> always fall back to parsing numbers as English formatted numbers if parsing them as numbers formatted using the user's locale fails P2 ASSIGNED
1200585 when RecomputePosition optimization moves an element, we don't move fixed positioned elements whose hypothetical box comes from that element P3 NEW
1205133 Ship inputmode=numeric P3 NEW
1220048 Disabled child element doesn't produce mousedown, mouseup and click events P3 NEW
1231147 SVG elements don't support CSS rem units for height/width attributes P3 UNCONFIRMED
1235045 Date Formats Support -- NEW
1246727 "-moz-appearance: button" doesn't hide a <select>'s downarrow button, on Android -- NEW
1248570 Firefox can't play wav in video or audio element P3 NEW
1256980 "z-index" has an effect on transformed content in Firefox, but not in Edge/Safari/Chrome -- NEW
1273010 Blocky and slow rendering on Firefox Android Nightly - filter: drop-shadow() P3 ASSIGNED
1273836 Copy-Paste of simple HTML adds extra new lines that are not present in original content -- UNCONFIRMED
1274354 [meta] Date.parse, amirite P3 NEW
1289682 Relatively-positioned table-row behaves as absolute containing block in Firefox (unlike other engines) -- NEW
1304733 insertRule on cross domain style sheet throws an exception in FF but not Chrome, Edge, IE P3 NEW
1306590 percent "text-indent" values resolve against the wrong container box, for overflow:hidden elements (causing stray character to be visible at reddit) P3 NEW
1307024 [Perf] [google docs] Firefox will get 3~9% faster when running gdoc test cases with chrome user agent -- NEW
1307118 Firefox 49 Does not Show Events in Scoutbook Calendar (background color of text field not rendering) P3 NEW
1307678 Title of latest recommendation of is cut P3 NEW
1316534 [css-flexbox] A non-default "flex-basis" incorrectly prevents min-size:auto from being clamped by specified size -- NEW
1319215 The "Contre Jour" game does not start P3 NEW
1322694 WebGL video textures fail to render in Firefox Nightly for MP4 format with 2048x1024 pixels dimensions P3 UNCONFIRMED
1324307 Ensure that -moz-device-pixel-ratio behavior matches -webkit-device-pixel-ratio P3 NEW
1328474 background: 0 and -moz-appearance: none suppresses the checkmark on input checkbox -- NEW
1328475 Give "-moz-user-select:auto" special spec-defined inheritance-like computation behavior P3 NEW
1331793 Consider not throwing on querySelector("::-webkit-scrollbar") P3 NEW
1332959 RTL web pages are aligned on the left side when the viewport is too small for the content P3 NEW
1335627 In quirks mode, toplevel "height:calc(%)" is treated as "auto", unlike raw percent heights (which are honored) P3 NEW
1336245 Geolocation should return available low-res location when high-res location is not yet available P2 NEW
1337114 Diacritics rendered incorrectly with decomposed unicode and Proxima Nova P3 NEW
1338656 ES_texture_float extension seems to not be found on Android devices where Chrome finds it. P3 NEW
1340064 [viewport] user-scalable, min-scale and max-scale will be ignored starting with iOS10 P3 NEW
1342445 Bad panning and zooming performance and huge memory usage (>10GB) on P3 NEW
1342569 mouseenter/mouseleave fire differently on <select>s in e10s mode. P3 NEW
1343096 Inner/submenus on are broken P3 NEW
1353248 [e10s] select - options styling doesn't work properly if CSS selector :-moz-focusring is present P3 NEW
1360238 window.getSelection().toString() displays extra "\n" characters on multiple block elements, even if they are display:inline P3 UNCONFIRMED
1362499 Support unit-less values for CSS -webkit-perspective (for interop) P3 NEW
1362898 content with ::before gets painted at the wrong place -- NEW
1362907 option text in select element with min-height is top aligned instead of centered -- NEW
1365806 empty element has an offsetheight if given overflow-y:scroll, unlike other browsers P3 NEW
1366115 SVG element with artifacts at certain sizes (on -- NEW
1371386 Firefox does not prefer Apple Color Emoji to Times New Roman on OSX, but Chrome/Safari do. P3 NEW
1372325 Allow the same SpeechSynthesisUtterance to be played multiple times in speechSynthesis.speak() P3 NEW
1373826 Wifi purchase form onboard IcelandAir broken (credit card textfields in flex container are too wide) P3 REOPENED
1375720 svg icons on GitHub are blurry (and unevenly so) P3 NEW
1376369 -moz-user-select:none triggers dragging also when @draggable="false" P3 NEW
1378447 Arrow buttons misaligned on mobile view of P3 NEW
1380217 Implement non-standard WheelEvent.wheelDelta properties P3 NEW
1381911 Bug 1359527 broke the radient gradient fade on P3 NEW
1382471 Firefox wraps word-broken text under a previous float-left, rather than starting it on the same line. P3 NEW
1383650 Implement SVG geometry properties in CSS P3 NEW
1385382 bullet with text-align:center is positioned further to the right in Firefox, as compared to other browsers (breaking fake radio button at P3 NEW
1385419 Parent element stretches to submit input's line-height, rather than its also-specified height. P3 NEW
1387483 [Meta-Bug] Support ReadableStream as Request.body in fetch API P2 NEW
1388931 Consider removing SVGPathSeg APIs P2 NEW
1390749 Flex item is extra-wide in Firefox, with "flex-basis: 100%; width: 100%" P3 NEW
1391109 tables inconsistently back-compute their intrinsic sizes from percent-sized cells (only when they're being *directly* intrinsically sized, but not inside intrinsically-sized container) P3 NEW
1392669 Left menu text does not always appear on page load for the Canvas-based game at P3 NEW
1394778 rel=preload for no-cache resources P2 NEW
1399019 Cannot play Facebook 360 video using Firefox P2 NEW
1400958 Text stomps on float with negative margin (with margin negative enough to zero out margin-box size) P3 NEW
1403410 Checkbox has 3 states – empty / outlined / with check-mark. P2 ASSIGNED
1404157 option element is being resized when applied a CSS height P3 NEW
1405682 Implement the decode() method on images P3 NEW
1406116 Negative right margin on element inside inline-block element forces text-wrapping on Firefox, not on other browsers. P3 NEW
1407496 Flash Player not loaded or notification to activate P3 NEW
1409490 meta-viewport makes elements with inner :active content unclickable. P2 NEW
1409529 SVG images with width or height only set in CSS rules are not visible (in intrinsically-sized block, e.g. flex item or float) P3 NEW
1411862 Disable 3rd party cookie video does not play in Firefox Dev Edition (v57 with uBlockO). P3 NEW
1414402 Support playback of mp4v video P5 NEW
1415789 -moz-appearance button-bevel should behave like -webkit-appearance: button-bevel P3 ASSIGNED
1417753 Implement -moz-appearance: searchfield-cancel-button which behave like -webkit-appearance: searchfield-cancel-button P3 NEW
1418472 Wrong position of github issue name on hover P3 NEW
1419610 Radio buttons are not visible in Firefox Android while visible in Chrome. P3 NEW
1421157 -moz-appearance: inner-spin-button should render arrow down + arrow up button P3 NEW
1421318 Google Translate: Unable to insert cursor into block of text P2 NEW
1421597 Provide an option to ignore scroll events outside of the control when a |select| drop-down is open P3 NEW
1422891 [Rethink] Support mkv|matroska|video/x-matroska in Firefox P3 UNCONFIRMED
1425291 Implement support for the autocapitalize atttribute P3 NEW
1427020 The site stops loading up to this graphical level P3 NEW
1427678 Scrollbars are covering part of a box when scrolling with a trackpad on a touch screen enabled laptop P3 NEW
1428236 In some occasions, navigating back and forth at the site causes the website to be zoomed in yet not resizeable P3 NEW
1428252 Scripts don't load P3 NEW
1428263 Incorrect layout (position) for position:fixed child of transformed scrollable flex container P3 NEW
1430989 “Weiteres Land hinzüfugen” (“ + Add another country”) button has design issues P3 NEW
1434236 Caption width set to 100% in a table has the width of the document and not the table width P3 NEW
1436225 blocking script and cpu high with SetTimeout P3 NEW
1436227 Unnecessary empty option displayed in the “發票” drop-down menu P3 NEW
1436801 Vertical padding influences baseline alignment of text around span with "vertical-align:middle" (only in Firefox) P3 NEW
1437413 Characters descenders cut out in an html input P3 NEW
1437761 position:sticky inside partially-offscreen position:fixed container has a different behavior in Chrome/Edge vs Firefox P3 NEW
1438105 javascript: doesn't work when a:active {position:relative} is set on a href on Firefox Android P3 NEW
1438398 After opening then closing the Account panel (top-right blue-ish icon), the page doesn't reflow correctly. P3 NEW
1439492 pseudo selector :after/:before + content has no effect on input type=checkbox P3 NEW
1441089 br with height: 0 still creates a line break in Chrome, Safari and Edge but not in Firefox. P3 NEW
1443284 percentage height in auto-height table cell in fixed-height table is treated as auto P3 NEW
1447230 big grey block hide the text when scrolling on Firefox Android P3 NEW
1447524 Double session history entries from P2 NEW
1448776 Allow line-break after - (U+002D / hyphen-minus) between digits. P4 NEW
1449079 PNG background-image icon not positioned at the right place after first rendering P3 NEW
1449753 Turn off layout.css.moz-document.url-prefix-hack.enabled by default. P3 NEW
1450173 input with date/time type doesn't center its contents, with "text-align:center" P3 NEW
1450595 Click to flash not working on macos P3 NEW
1450815 HTTP POST receives a response with a onload event in JS posting to itself and generating an infinite loop P3 NEW
1450842 Videos could not be decoded P3 NEW
1451981 The "Book" dropdown menu appears behind other content in the page. P3 NEW
1451998 the thumbnails all play automatically at the same time, and the website gets so slow it's impossible to use. P3 NEW
1452017 The animation of transition when pressinng the next button is jittery. P3 NEW
1452646 while clicking and navigating back, an outline is drawn P3 NEW
1453797 Carousel images have jagged edges when scrolling through P3 NEW
1454043 Carousel images have jagged edges when scrolling through P3 NEW
1454289 WebGL doesn't load, black screen P3 NEW
1454290 Automatic Caption does not work P3 NEW
1455545 Noto Sans Symbols is not rendered on some Android devices P3 NEW
1456052 Small allocated space for “Comments” hint text field P3 NEW
1457805 Images flickering and slight jankiness because of CSS animations P3 NEW
1459535 Performance is incredibly degraded when idle on P3 NEW
1460186 input type=file is sensitive to height (while chrome and safari don't) P2 NEW
1461246 When editing the Note field in, browser scrolls up. I'm thus typing blindly P3 NEW
1461264 RGB Color space/profile seem different (pictures appear darker in Firefox than in Edge) P3 NEW
1461266 comments framerate is smoother on Chrome than Firefox P3 NEW
1463335 anchor and input superposed makes the JavaScript non active. P3 NEW
1463402 Implement Picture-in-Picture Web API P3 NEW
1464925 Visual glitch: graphic layers around menu displaced, linked to scroll position. P3 NEW
1466441 Skin color changes don't stick at (race condition?) P3 NEW
1467114 BBC - highlighter for navigation spans extends to body edge P3 NEW
1469731 Menu is blurred after transition P3 NEW
1470315 The layout becomes blurry when the page is scrolled down/up P3 NEW
1471110 slideshow doesn't work P3 NEW
1471123 Can't play video error message on Firefox Android P3 NEW
1471232 iframe content overflow spontaneously after a couple of seconds P2 REOPENED
1472582 td containing nowrap='' and a fixed width will grow (while Chrome with enforce the width) P3 NEW
1472941 Slow loads and performance at, compared to Chrome P3 NEW
1473495 Flash of Unstyled Content (not happening in Chrome) P3 NEW
1473501 Improve the way Gecko selects images based on srcset values (don't just round up, when rounding up is a huge jump) P3 NEW
1473789 {inc} intrinsically-sized inline-block with orthogonal writing-mode content has size of 0 on the first reflow and correct sizes later P3 NEW
1475396 Select will not dropdown on-click when unfocused, given the CSS :focus { position:relative } P3 NEW
1475681 Page CSP can break seeking to unbuffered position (in mp3 playback) P2 REOPENED
1475723 Geckoview and Fennec open select dropdown on tap of parent label; other browsers do not. P3 NEW
1476051 Interop issues with select element styling with appearance:none. P3 NEW
1476812 left:auto on a position:absolute display:inline-block element shouldn't consider floats after the inline-block that would have moved it P3 NEW
1476925 Negative margin doesn't cancel the padding on parent causing undesired line breaking when width is auto P3 NEW
1477110 Select elements seem to get double the text-indent when a percentage is specified. P3 NEW
1479321 Hovering "A propos" sub-menu with the mouse displays the menu for a split second and disappears P3 NEW
1481112 User Agent Stylesheet Default for select, button P3 NEW
1481124 Menu takes longer to open in Firefox than in chrome P3 NEW
1481132 [Android] flashes 3 times when you reload or navigate away P3 NEW
1481581 [meta] More closely align the behavior of '-moz-appearance' with Chrome's '-webkit-appearance' P3 NEW
1481596 Make `-moz-appearance: none` on <textarea> behave more like Chrome P3 NEW
1486362 CPU usage is extremely high at P3 NEW
1486365 The City selection page slightly bounces after opening P3 NEW
1488334 White dots are visible along the Rubik's Cube edges P3 NEW
1490873 Toggling SVG graph elements on and off leaves artifacts and erases parts. P3 NEW
1491743 invalid CSS property value on ::selection kills the default selection settings P3 NEW
1492361 Tracking issues with SSL_ERROR_NO_CYPHER_OVERLAP P1 NEW
1492818 After resizing the browser, the page is not reloaded and the resulted empty space becomes unusable. P3 NEW
1493271 Clicking on "share icons" does not open new window P2 NEW
1493434 Inconsistent table column sizing between Firefox and Chrome (with percent sizes on colgroup and col) P3 NEW
1493561 non-specified border-width on input element is wide on Ubuntu P3 NEW
1494157 background-size: cover differs from Chrome/Safari (with background-attachment: fixed, on mobile viewports) P5 NEW
1495868 Unprefix -moz-fit-content and -moz-available keywords P3 NEW
1497375 Page repeatedly jumping toward the end of the page when scrolling P3 NEW
1497742 CSP with invalid U+00A0 character P3 NEW
1497959 clip-path: inset(0 0) cuts off content if it is too long when not using WebRender -- NEW
1498729 Updating the content for a viewport meta tag should discard old values P2 NEW
1499986 Handling return value for a script P3 NEW
1501480 mask-image and SVG on input element fails in Firefox, Safari, and Edge, works in Chrome P3 NEW
1502150 getComputedStyle difference between Fennec and Desktop (at least for WebkitAppearance values) -- NEW
1502769 Scrolling is janky when partial menu is sticked to the top of the viewport. P3 NEW
1503241 The CloudShell on Google Cloud Platform does not load (prompt missing) P2 NEW
1503427 Firefox 63 pushing Bootstrap 3 date input text down P3 ASSIGNED
1503899 Sharp printer UI incorrectly rendered, due to table-layout behavior difference (& with CSS enabled by webkit-min-device-pixel-ratio query) P3 NEW
1506487 - video not playing, OS needs to be restarted. P3 NEW
1507744 word-break: break-all on an inline doesn't cause breaks P3 NEW
1508177 Consider shrinking content even if no content area gets visible P3 NEW
1510138 Incorrect shadows on asset buttons P3 NEW
1511150 GitHub emoticon glyphs sometimes appear "cut off" P3 NEW
1513435 Incompatible column layout with 'height:0' and definite 'column-width' P3 UNCONFIRMED
1514269 [CSS Multicol] Firefox only web platform tests P2 NEW
1514362 [CSS Selectors] Firefox only web platform test failures P3 NEW
1514367 [CSSOM View] Firefox only web platform test failures P2 NEW
1514371 [CSSOM] Firefox only web platform test failures P2 NEW
1514538 SVGMatrix and DOMMatrix are not interchangeable in Path2D.addPath P3 NEW
1514630 - WebGL errors once we fake UA to be chrome and bypass UA sniffing P3 NEW
1514655 Plaintext documents in subframes (or <object>) don't get word-wrapping P3 NEW
1517388 Can't click on links on (animation and preserve-3d related) P2 REOPENED
1517666 quick zoom in and out will white out Firefox and all tabs P3 NEW
1518040 SVG feBlend should take account of flood-opacity on feFlood input nodes P3 NEW
1520157 SourceCodePro font rendered in wrong colour on osx P2 NEW
1520983 Interop issues with composition events and IMEs like the OSX emoji picker P3 NEW
1521631 Implement overflow:overlay (non-standard) as an alias of overflow:auto P2 NEW
1521660 Adding a selected and disabled option as the first of a select's list of options forces the first user selection to be the first option after it. P3 NEW
1521882 SVG without width/height specified has different intrinsic-sizing behavior in Chrome vs Firefox (e.g. in a float or in flexbox) P3 NEW
1522319 translateZ(0) affects the scrollability of a menu on P3 NEW
1522706 History.pushState limit may be too low for some live sites -- NEW
1523231 Screen problems not everything is there P3 NEW
1523541 window.innerHeight changes with the dynamic toolbar on Firefox P3 NEW
1526776 Scroll position back to previous position, or sometimes, flicker page. P3 NEW
1526855 select is wide when the label is wide in optgroup (not on Chrome) P3 NEW
1528043 Blink and Gecko differ on how wide to make the input in this floating test-case P3 NEW
1528305 Behavior on location.href redirects to an unknown protocol can break pages. -- NEW
1528845 dynamic datalist is not working in Desktop + RDM and Firefox Android P3 NEW
1528882 - Navigation icons are incorrectly displayed -- NEW
1529471 objectBoundingBox, clip-path behave differently in Chrome and Firefox P3 NEW
1529953 Consider supporting the legacy mousewheel event for interop. P3 NEW
1530577 (Un)Expected HTTPS upgrade of download due to <meta ... "upgrade-insecure-requests"> tag P3 NEW
1531888 If clip-path IRI is missing, Firefox does not ignore it (at least for the purposes of mouse-interactions). P2 NEW
1532481 Firefox does not expand certain list items so they do not vertically overlap, as other engines do. -- NEW
1533151 Gecko and Blink disagree on where to place abs.pos. children of fragmented inline CB P3 NEW
1533630 Gecko fires click events for middle and right clicks, against the uievents spec. P2 ASSIGNED
1534863 Wrong scrolling behavior when opening sections P3 NEW
1539053 Rotating and/or moving text in creating a new story is very slow and choppy. P3 NEW
1540603 Gzip JavaScript file is not properly decoded with illegal character P3 NEW
1541330 Speech Synthesis play incorrect P3 NEW
1541964 Input with line-height: 1 may cut off parts of the text, unlike Blink. -- NEW
1542989 Page is blank due to early HTTP negotiation P3 NEW
1542995 Thousands of window.onload events creates high memory/CPU until it crashes P3 NEW
1543059 Loading spinner displays at end of some non-looping videos hosted on P2 NEW
1544428 Setting window.location.hash to an empty string on a site without a hash causes a popstate event -- NEW
1544455 WebVTT cue class spans get rendered as block elements instead of inline elements P3 NEW
1544488 Combining Diaeresis in webfont cause extra spacing P3 NEW
1544649 Site with a fixed width is not zoomed in Firefox, zoomed in Chrome P3 NEW
1544676 window.stop() and window.loading = true seems to block P3 NEW
1545659 A horizontal scroll bar is displayed under the categories section when the page is loading P3 NEW
1545702 SVG text without textspan doesn't render under certain circumstances P3 NEW
1545703 - Some videos do not play or play erratically P3 NEW
1545797 Cookie restrictions strict list is blocking the use of Amazon Pay -- NEW
1546049 input checkbox left border is not visible under certain circumstances on mobile P3 NEW

259 Total; 259 Open (100%); 0 Resolved (0%); 0 Verified (0%);


This is the Yeah! Let's party list.

WebKit Flexbox Total Armaggedon in China and Japan

This is not specific to Desktop and Mobile, but more to the specific markets of China and Japan and indeed more often on mobile.

Suggested Fix Use Web standards flexbox properties in addition to the WebKit ones if old devices compatibility is required.

Related Bugs


Many sites have code that detects touch support and assumes mouse input can be ignored. These sites behave oddly on all computers that have a touch screen AND a mouse - usually not responding as expected to mouse input.

Suggested Fix Write JavaScript that will handle both click and touch input, not either-or.

Related Bugs


(Fixed in Gecko) Basically an image with a max-width: 100% was bigger than the viewport It was an issue, created by a different behavior in Gecko and Blink. But the market share of Blink imposed the unspecc’ed behavior of Blink.

Suggested Fix The fix was often a combination of display: table with table-layout: fixed. This is now fixed in Gecko and the spec, but this is a good illustration point in terms of Web Compatbility issues.

Related Bugs

Video streaming using Apple’s proprietary HTTP Live Streaming

Firefox doesn’t support this on Desktop or Mobile.

Suggested Fix Not a trivial thing to fix. Ensure that there is a fallback mechanism for browsers that don’t support HLS (currently on Desktop, only Edge and Safari do).

Related Bugs

Meta viewport fixed size

Very similar to the max-width bug. This is a different of behavior in between blink and Gecko. Basically with a fix width, Gecko on Mobile doesn’t necessary resize the page to fit in the screen.

Suggested Fix Use width=device-width instead of fixed size.

Related Bugs

Faulty UA detection

Sites sniff the user agent string, often to figure out if you’re using a “supported browser”. This goes wrong all the time, because of an unknown UA string, or parsing bugs, or not understanding versions greater than 9, etc. Mobile browsers will frequently end up on “Desktop” sites, rather than mobile ones as a result of this kind of bug.

Suggested Fix Update your UA detection library or framework, or use feature detection rather than relying on User Agent string parsing. User Agent detection is about detecting the past. So it will obviously fail. Feature detection is about inspecting the now.

Related Bugs

Relying on global event object

WebKit (possibly copied from old iE?) has a non-standard global event object. When sites don’t pass in the event object to an event handler, we end up with exceptions like “ReferenceError: event is not defined”

Suggested Fix Use web standards and pass in an explicit event object into your event handlers. For example: a.addEventListener(‘click’, function(e){ blah(e)});

Related Bugs

HTTP Ping Pong

The company has two different sites: desktop and mobile with different domain names. They do user-agent sniffing be with HTTP user-agent header, through JavaScript.

Suggested Fix The issue starts to fix itself by people switching to responsive Web sites. The fix is actually simple. Which ever technique you are using should have a consistent policy in terms of user agent sniffing. Some websites make mistakes when the detection mechanism is not the same on both domains: for example one with HTTP, and one with JS. In HTTP only, the browser is able to identify the infinite loop and will stop after 10 iterations, but when switching from HTTP to JS and then to HTTP, etc the browser is really caught forever.

Related Bugs

Webkit Scrollbar

Websites would like to replace default scrollbars with custom ones. There are known issue of Firefox not hiding the default scrollbar and potential scrollbar lagging introduced with async scrolling (e10s-only).

Related Bugs