jQuery and the W3C

jQuery and Standards John Resig http://ejohn.org/ - http://twitter.com/jeresig

jQuery✦ A JavaScript library designed to hide painful cross-browser compatibility issues while presenting a solid, usable, API.

Simple API✦ $(“div > span”).addClass(“foo”); ✦ “Find some elements” ✦ “Do something with them”✦ Makes complex manipulation of web pages simple

Space✦ Highly competitive space✦ Released Jan. 2006 - already a dominant player: Prototype JavaScript Library✦ (Bundled with Ruby on Rails, had some nice coattail growth.)✦ Other libraries: Dojo, Yahoo UI, MooTools

Speciﬁcations✦ A few speciﬁcations that matter to us: ✦ DOM ✦ HTML ✦ CSS ✦ ECMAScript✦ DOM more than anything else.

Concerns✦ Performance.✦ Performance.✦ Performance.✦ Usability.✦ Any standards/browser addition that gives us performance beneﬁts we’ll leap on.

New Standards We’ve Used✦ Selectors API ✦ querySelectorAll✦ Selectors API 2 ✦ matchesSelector✦ Animation Timing ✦ requestAnimationFrame✦ ECMAScript ✦ bind

Selectors API✦ A bit of a failure✦ Didn’t listen to the needs of libraries✦ Missed a number of important features/ bug ﬁxes: ✦ Contextual searching is messed up ✦ Error reporting is non-existent ✦ Implementations are inconsistent✦ But it’s very fast, so we use it.

Matches Selector✦ Selectors API 2 gave us matchesSelector✦ We petitioned browsers to implement this✦ They did, then it became a standard✦ Makes our event delegation much faster

Smooth Animation✦ requestAnimationFrame was created✦ Scales animations based upon load✦ Unfortunately this broke user expectations (expected certain frame rates)✦ We just backed it out, will have to try again later

HTML string -> DOM support✦ No good way to do this now✦ Have to create a DOM element and use innerHTML✦ Clunky and quite slow✦ We want: ✦ someMethod(“<b>stuﬀ</b>”) -> ✦ [ <b> ]

Access to event callbacks✦ We want to be able to remove individual callbacks✦ We want to be able to clone callbacks✦ We want to be able to trigger speciﬁc callbacks✦ All of this requires access to callbacks

An event for when stylesheets load✦ Right now we have an event for DOM loaded✦ And an event for window loaded✦ But no event for when all the stylesheets load (important for looking at computed styles)

Will an element ﬁre an event?✦ For example - if I have a <form> element I want to be able to ask it: ✦ “Will you ever, natively, trigger a submit event?” (true)✦ If I ask a <div> if it will trigger a submit event, it will return false.

Unique ID for DOM nodes✦ We have to manage callbacks and data that we attach to DOM nodes✦ To do this we have to assign the nodes a unique ID✦ It’d be much better to have a property that took care of this for us

“Late Events”✦ There is no way to ask the browser: ✦ “Did an event [foo] already fire on this element?”✦ For example: ✦ Did the load event already fire on window? ✦ Did the submit event already fire on this form? ✦ etc.

Fast DOM mutation events✦ I know this is being worked on right now (yay!)✦ A way to have fast DOM mutation events would be awesome✦ It could allow for some really slick restructuring of applications✦ And make it easier for us to possibly do caching

mouseenter/mouseleave✦ Internet Explorer provides these events✦ They’re terribly useful (make it so that you don’t have to deal with event bubbling weirdness)✦ Should be in browsers✦ Need to verify DOM 3 Events spec

getComputedStyle✦ A complete mess right now✦ There is no consensus over what results should be returned and when✦ There needs to be something declared here - probably a joint venture between the CSS and DOM working groups.✦ Test suite for getComputedStyle

isCSSAuto✦ There is no way of determining if a CSS property is currently set to “auto”✦ This should be resolved, makes it much easier to do some types of animations

A way to sanely toggle visibility✦ If we’re given an element that is display: none and we want to make it visible (display: block, perhaps)✦ It is very hard to determine what the right “visible” style should be✦ Especially if someone does: ✦ div { display: none; }✦ Hint: It involves nasty use of iframes

contains() method✦ We have compareDocumentPosition✦ This is OK but contains() is very easy to use (in IE)✦ Easy enough to implement, should be a standard

Better way of sorting nodes✦ We have to use compareDocumentPosition now✦ This is very very slow✦ A numerical index property on nodes would be very useful (like in IE)

Is a node in an XML document✦ A number of behaviors change when you’re in an XML document✦ (IDs no longer resolve, some properties may not exist - like innerHTML, etc.)✦ A way to determine if we’re working against an XML document would help

Support Tests

Questions?✦ Questions? ✦ jeresig@gmail.com ✦ http://ejohn.org/ ✦ http://twitter.com/jeresig

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jQuery and the W3C

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