MutationEvents.txt

Our bug report to jQuery:

I've been building a library to make packaging behaviors simple. It works very
well against jQuery 1.4.2. However, the Sizzle included in 1.4.3 and 1.4.4
uses a technique to keep track of it's place in the DOM - it changes the id of
nodes as it traverses. In 1.4.3, it's about line 3904 of the unmini'd version.

When the id changes (at least in Chrome) a DOMSubtreeModified event gets
thrown. The trouble is, I've attached a handler to the document for DSM events
that needs to find the target Element - which triggers a DSM.

Is it reasonable for $().find(selector) to trigger an event?

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Their response:

Thanks for reporting this, but jQuery cannot provide support to deprecated
specs (the mutation events).

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Okay:

http://www.w3.org/TR/DOM-Level-3-Events/#events-mutationevents

Warning! The MutationEvent interface was introduced in DOM Level 2 Events, but
has not yet been completely and interoperably implemented across user agents.
In addition, there have been critiques that the interface, as designed,
introduces a performance and implementation challenge. A new specification is
under development with the aim of addressing the use cases that mutation
events solves, but in more performant manner. Thus, this specification
describes mutation events for reference and completeness of legacy behavior,
but deprecates the use of both the MutationEvent interface and the
MutationNameEvent interface.

and:

From http://www.w3.org/TR/DOM-Level-3-Events/#glossary-deprecated

deprecated
Features marked as deprecated are included in the specification as reference
to older implementations or specifications, but are optional and discouraged.
Only features which have existing or in-progress replacements shall be
deprecated in this specification. Implementations which do not already include
support for the feature may implement deprecated features for reasons of
backwards compatibility with existing content, but content authors creating
content should not use deprecated features, unless there is no other way to
solve a use case. Other specifications which reference this specification
should not use deprecated features, but should point instead to the
replacements of which the feature is deprecated in favor. Features marked as
deprecated in this specification are expected to be dropped from future
specifications.

But: 

http://www.w3.org/2008/webapps/wiki/MutationReplacement#Widgetify_dynamically_created_markup
(being the closest use case to NinjaScript)

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there's no replacement.  There are suggested replacements, but nothing
implemented.  Firefox and Webkit both support parts of the MutationEvent
interface, but no one supports watchSelector (even Microsoft, who suggested
it) or XBL2 (even Mozilla who implemented XBL1 and submitted it to the W3C).
So, if you want to know when elements are added or changed in the DOM, you
have 3 options:

1. Use the deprecated, implemented DOM3 events
2. Notify yourself every time you change the DOM - just don't forget. (This is
how we cope in IE.)
3. Poll the document with querySelectorAll() - which also won't work in <=IE8


Q: Why not just use $().live()?
A: Can't do transforms

Q: Is NinjaScript quixotic?  Do we need this?
A: I think there's a benefit.