clj in course material

[Karl Tikjøb Krukow]

I am preparing an introductory course on JavaScript for the place I work
at. As part of the course, I would like present some of the common
knowledge and generally accepted advice of this group, since it is not
commonly known and it should guide them in the right direction.

(A small) part of this is on general purpose libraries. I've exported
the slides as a set of html documents which can be found here:

<http://higher-order.net/courses/05-js-libraries.html>

I would appreciate feedback from the group. Remember that this is an
introductory course to it should be kept to basics and generally
accepted statements.

- is it accurate (enough for an introductory course)?

- are the examples OK?

- is something important missing?


Additional questions on attribution:

- Did Cornford or Crockford invent the module pattern?

- Who created the initial "clone/object/beget/Object.create": Cornford,
Crockford or Reichstein Nielsen?

Thanks for your time
/Karl

 

[Gregor Kofler]

Am 2010-07-27 09:59, Karl Tikjøb Krukow meinte:

I am preparing an introductory course on JavaScript for the place I work
at. As part of the course, I would like present some of the common
knowledge and generally accepted advice of this group, since it is not
commonly known and it should guide them in the right direction.

(A small) part of this is on general purpose libraries. I've exported
the slides as a set of html documents which can be found here:

<http://higher-order.net/courses/05-js-libraries.html>

I would appreciate feedback from the group. Remember that this is an
introductory course to it should be kept to basics and generally
accepted statements.

Some things I noticed when quickly browsing through some slides:

"Normalization: DOM Nodes - Some libraries provide their own types"
Libraries can't provide their own (read: custom) *DOM* nodes. Perhaps
some node-lookalikes.

"Be vary of augmented HTML*Elements" - better: "Be wary of augmented
host objects"

"Element types"? I'd call it "Wrapped DOM elements".

Gregor

 

[Karl Tikjøb Krukow]

Am 2010-07-27 09:59, Karl Tikjøb Krukow meinte:

Some things I noticed when quickly browsing through some slides:

"Normalization: DOM Nodes - Some libraries provide their own types"
Libraries can't provide their own (read: custom) *DOM* nodes. Perhaps
some node-lookalikes.

"Be vary of augmented HTML*Elements" - better: "Be wary of augmented
host objects"

"Element types"? I'd call it "Wrapped DOM elements".

Gregor

Thanks for taking the time, Gregor. I'll make the suggested changes.

/Karl

 

[RobG]

I am preparing an introductory course on JavaScript for the place I work
at. As part of the course, I would like present some of the common
knowledge and generally accepted advice of this group, since it is not
commonly known and it should guide them in the right direction. [...]
Additional questions on attribution:

- Did Cornford or Crockford invent the module pattern?

Its history in this group is summarised by Richard Cornford here:

FAQ Topic - How do I format a date with javascript? (2009-02-26)
<URL: http://groups.google.com.au/group/comp.lang.javascript/msg/4947717f130ca6e5?hl=en
He claims credit (probably quite rightly) for building on the early
work of Yann-Erwan Perio and Gosha Bine to develop the pattern that is
in current use as the module pattern.

- Who created the initial "clone/object/beget/Object.create": Cornford,
Crockford or Reichstein Nielsen?

I believe the pattern that Crockford popularised with beget was
originally proposed here by Lasse Reichstein Nielsen:

Using setInterval inside an object
<URL: http://groups.google.com/group/comp.lang.javascript/msg/5d06e72e55d5bf11?pli=1

<FAQENTRY>
Perhaps some of the above can be inclued in a "history of javscript"
section of the FAQ so that such things aren't lost.
</FAQENTRY>

 

[Richard Cornford]

I am preparing an introductory course on JavaScript for the place I work
at. As part of the course, I would like present some of the common
knowledge and generally accepted advice of this group, since it is not
commonly known and it should guide them in the right direction.

(A small) part of this is on general purpose libraries. I've exported
the slides as a set of html documents which can be found here:

<http://higher-order.net/courses/05-js-libraries.html>

I would appreciate feedback from the group. Remember that this
is an introductory course to it should be kept to basics and
generally accepted statements.

Slide img2.html

"The goal for JavaScript libraries is to present an API which

- us uniform and more high-level, yet efficient.
- works around known bugs
- supports a wide range of user agents."

The "supports a wide range of user agents" is demonstrably false in
almost all cases. Most javascript libraries aim to support a fixed set
of user agents, and quite a restricted set at that.

slide img3.html

"Most libraries provide
* ... , Keyboard normalization ..."

Mostly they don't. Keyboard normalisation (so between event models and
key event behaviour, Hardware variations, OSs (which must include non-
desktop OSs) and language related keyboard layout) is complex subject
that is rarely more than superficially addressed in library code.

Slide img5.html

"Be vary of augmenting HTML Elements" probably contains a typo.

Slide img7.html

"Least common denominator, e.g., event capture"

Shouldn't that be event bubbling, as its capturing that IE doesn't do?

Slide img8.html

"This is considered bad practice, a hack, by many.
- Unreliable
- Restricted accessibility
- Maintenance"

I don't think that "accessibility" has much direct relevance to
browser sniffing. It can be restricted as much without it as with it.

As this related to UA string based browser sniffing why doesn't the
list of reasons for considering it "bad practice, a hack" (which is a
considerable understatement in many cases) include the observation
that it has no technical foundations (i.e. that there are no technical
grounds for believing that it should be possible to determine browser
type or version from any User Agent header/string). Given that the
pertinent standard (the HTTP 1.1 standard) does not even require that
a user agent send the same sequence of characters in its User Agent
header for two consecutive requests (let alone that it should contain
anything specific, let alone specific to the browser or its version).

The relevance of this is highlighted by 'arguments' in favour of
browser sniffing such as:-

<URL: http://blog.davglass.com/2009/01/browser-sniffing-vs-object-detection/
| That would be like me changing the information on my license
| plates and then telling the officer: "You should have checked
| the VIN instead of the license plate, I didn’t like what it
| said so I changed it".

- where that analogy implies some sort of 'law' being broken. While
the applicable 'law' actually says the UA string can be anything
anyone wants, and doesn't even have to be the same thing from one
occasion to the next. The real automobile analogy for the UA header/
string is not with a licence plate, but rather with something like a
bumper sticker; if you don't like it you may change it at your own
discretion, and no "officer" has any reason to question you about it
(at least assuming it is not offensive, an incitement to violence/
crime, etc.).

The observations that there is no technical basis for the belief that
you can discriminate between web browsers/browser versions using the
User Agent header/string, that web browser default User Agent headers
have been observed as being indistinguishable from those of other
browsers, and that User Agent headers can, in some circumstances, be
modified by users (and third party software) should be enough to
convince the rational that "bad practice, a hack" is an extremely mild
label to attach to the folly of browser sniffing.

Slide img10.html

The - typeof el.childNodes // 'function' - example for Safari is
probably inappropriate in context as the childNodes collection can be
called in that environment and so is a function, making the behaviour
fully conforming with the ECMAScript behaviour for a native function.

Slide img15.html

The "Potential cons" list:-

- Does not mention that the libraries are rarely actually cross-
browser (but merely support a limited set of brewers, so are actually
little more than an elaboration of the "both browsers" scripts from
the end of the last century).

- Does not mention that any 'community' is no more than the sum of the
people who participate in it, and that if the users of a library are
doing so because they don't know enough to do anything else (or
better) then their potential to offer help may be severely
constrained. (For example, while it existed the JQuery 'community' on
Google groups did not even answer between a quarter and a third of the
questions asked there, which was of zero 'help' to the people asking
those questions)

- Does not mention that the quality of library documentation can be
very poor, especially when the authors of the documentation either do
not understand what their code actually does, (and/)or believe that
what it does is obvious.

(There is a general documentation dilemma where the people who
understand cannot easily think themselves into the position of those
that don't, and so cannot see all of what needs to be put across, and
the people who don't understand can see what they would need to be
told, but cannot tell it.)

- is it accurate (enough for an introductory course)?

It would be very difficult to tell without the actual text.

- are the examples OK?

I didn't like any of the feature test examples. There didn't seem to
be a statement of the basic feature testing principle that wherever
possible you design a test that has the closest possible relationship
with the thing that you need to know; preferably a one to one
relationship. Rather than demonstrating this principle in action some
of the tests were pushing object inference.

- is something important missing?

Additional questions on attribution:

- Did Cornford or Crockford invent the module pattern?

Invent (which, in principle, many people may do independently), invent
first, or publish first?

Dougless Crockford has never claimed to have invented the "module
pattern" (and has sufficed intellectual integrity that he never will).
All attributions to him are indirect, third party, and not based on
any actual knowledge.

To the best of my knowledge, I published the first example of the
archetypal "module pattern" (the specific example from the YUI blog
article), having previously published numerous variations on the
theme, most of which would generally be agreed to be examples of the
'module pattern' in the wider sense (though many of them were things
that others have since re-invented and given other names to as
derivatives of the "module pattern").

It is possible that one of the other people developing/expanding on
previous examples of mine actually hit the archetypal "module pattern"
first. Finding out would probably take working thorough the entire
archive for the group between May and August 2003.

- Who created the initial "clone/object/beget/Object.create":
Cornford, Crockford or Reichstein Nielsen?

If you mean a pattern where an object is assigned to the - prototype -
property of an empty function and then that function is used to
construct a new object as a 'clone' of the original object, then
Reichstein Nielsen published the first example that I noticed.

Richard.

 

[RobG]

I am preparing an introductory course on JavaScript for the place I work
at. As part of the course, I would like present some of the common
knowledge and generally accepted advice of this group, since it is not
commonly known and it should guide them in the right direction.

(A small) part of this is on general purpose libraries. I've exported
the slides as a set of html documents which can be found here:

<http://higher-order.net/courses/05-js-libraries.html>

I would appreciate feedback from the group.

Slide 12:

The example code doesn't appear at the quoted link, it seems to have
been replaced by a new function. Perhaps you should quote the version
of the code or the date when it was quoted.

<URL: http://github.com/dperini/nwmatcher...a3fb9d9d0fe93d9a9f5e3f1/src/nwmatcher.js#L278

 

[Karl Tikjøb Krukow]

Richard Cornford wrote:
[snip..]

Slide img2.html

"The goal for JavaScript libraries is to present an API which

- us uniform and more high-level, yet efficient.
- works around known bugs
- supports a wide range of user agents."

The "supports a wide range of user agents" is demonstrably false in
almost all cases. Most javascript libraries aim to support a fixed set
of user agents, and quite a restricted set at that.

Agreed, there is a difference between an ideal library and what most
libraries do in practice.

I will rephrase it as ".. support several popular user agents".

slide img3.html

"Most libraries provide
* ... , Keyboard normalization ..."

Mostly they don't. Keyboard normalisation (so between event models and
key event behaviour, Hardware variations, OSs (which must include non-
desktop OSs) and language related keyboard layout) is complex subject
that is rarely more than superficially addressed in library code.

Agreed - I'll remove that and explain this point in the "potential cons"
slide.

Slide img5.html

"Be vary of augmenting HTML Elements" probably contains a typo.

That is now "host objects" taking Gregor's comment into account.

Slide img7.html

"Least common denominator, e.g., event capture"

Shouldn't that be event bubbling, as its capturing that IE doesn't do?

That bullet is poorly phrased, event capture was meant as an example of
a feature that is unsupported.

Slide img8.html

"This is considered bad practice, a hack, by many.
- Unreliable
- Restricted accessibility
- Maintenance"

I don't think that "accessibility" has much direct relevance to
browser sniffing. It can be restricted as much without it as with it.

Again, I've used an incorrect word. I mean accessibility to many user
agents - not users. I will rephrase (though I haven't got a concise word
now...)

As this related to UA string based browser sniffing why doesn't the
list of reasons for considering it "bad practice, a hack" (which is a
considerable understatement in many cases) include the observation
that it has no technical foundations (i.e. that there are no technical

[snip..]

Good point. I will move it to a separate slide to make room, and I will
elaborate on this and the corresponding misconception.

Slide img10.html

The - typeof el.childNodes // 'function' - example for Safari is
probably inappropriate in context as the childNodes collection can be
called in that environment and so is a function, making the behaviour
fully conforming with the ECMAScript behaviour for a native function.

Ok, the IE example should suffice to prove the point.

Slide img15.html

The "Potential cons" list:-

- Does not mention that the libraries are rarely actually cross-
browser (but merely support a limited set of brewers, so are actually
little more than an elaboration of the "both browsers" scripts from
the end of the last century).

Ok, I've added a bullet "Rarely supports more than a handfull of browsers"

- Does not mention that any 'community' is no more than the sum of the
people who participate in it, and that if the users of a library are
[snip..]

- Does not mention that the quality of library documentation can be
very poor, especially when the authors of the documentation either do
not understand what their code actually does, (and/)or believe that
what it does is obvious.

[snip..]

I'll combine these two into the advice to consider the quality of
documentation and community/commercial support options.

It would be very difficult to tell without the actual text.

Fair enough. A hope that, at least on the superficial level of
"bullets", it is accurate enough.

I didn't like any of the feature test examples. There didn't seem to
be a statement of the basic feature testing principle that wherever
possible you design a test that has the closest possible relationship
with the thing that you need to know; preferably a one to one
relationship. Rather than demonstrating this principle in action some
of the tests were pushing object inference.

Ah, this is important to me. First, I will include a description of the
principle - do you mind if I quote you on the above in the slides?

Second, Example 1 (taken from Peter's blog) was included because it is
fairly simple to understand. Do you have a reference to an example you
would consider more appropriate as a simple example?

Examples 2 and 3 are there to show that more advanced tests can be
devised (event support and testing for bugs). Although the test on event
support doesn't not directly test what I want to know (since simulating
e.g. mouse movement, is hard as discussed by kangax on his blog), it is
an example of not having to "give up" and do browser detection.

Of course, even more illustrative examples are welcome

Invent (which, in principle, many people may do independently), invent
first, or publish first?

I did mean publish first.

Dougless Crockford has never claimed to have invented the "module
pattern" (and has sufficed intellectual integrity that he never will).
All attributions to him are indirect, third party, and not based on
any actual knowledge.

To the best of my knowledge, I published the first example of the
archetypal "module pattern" (the specific example from the YUI blog
article), having previously published numerous variations on the
theme, most of which would generally be agreed to be examples of the
'module pattern' in the wider sense (though many of them were things
that others have since re-invented and given other names to as
derivatives of the "module pattern").

It is possible that one of the other people developing/expanding on
previous examples of mine actually hit the archetypal "module pattern"
first. Finding out would probably take working thorough the entire
archive for the group between May and August 2003.


If you mean a pattern where an object is assigned to the - prototype -
property of an empty function and then that function is used to
construct a new object as a 'clone' of the original object, then
Reichstein Nielsen published the first example that I noticed.

Richard.

Thanks for the clarifications.

Kind Regards,
Karl.

 

[Karl Tikjøb Krukow]

Slide 12:

The example code doesn't appear at the quoted link, it seems to have
been replaced by a new function. Perhaps you should quote the version
of the code or the date when it was quoted.

<URL: http://github.com/dperini/nwmatcher...a3fb9d9d0fe93d9a9f5e3f1/src/nwmatcher.js#L278

Yes, valid point. I modified the code - that should be pointed out.

Thanks.
Karl

 

[Karl Tikjøb Krukow]

Richard Cornford wrote: [snip]

The "Potential cons" list:-

- Does not mention that the libraries are rarely actually cross-
browser (but merely support a limited set of brewers, so are actually
little more than an elaboration of the "both browsers" scripts from
the end of the last century).

Ok, I've added a bullet "Rarely supports more than a handfull of browsers"

[snip]

Trade-off: if and what library to use
Potential pros:
- Responsibility of handling most cross-browser concerns are pushed to
the library developers

- Common utility functions and reusable components

- One place to go for documentation, and a single community

Potential cons:
- You may not be happy with all the solutions that library developers
have chosen, nor consistency of all APIs

- Rarely supports more than a handfull of browsers

- Varying quality of documentation and support

- Browser detection requires continous maintainance/upgrades

- Monolithic/non-modular libraries will inevitably contain many features
that you won't use

- Libraries will inevitably not contain all you need. Extensibility is
useful.



Advice on libraries

* Consider your context
- General web vs. intranet.
- Accessibility requirements?
- Constrained devices? Unknown devices?
- App-in-a-page or hyper-text document? In between?

* Be aware of the costs and benefits of using a particular library or not
- Make an informed decision
- Don't include a library “by default”
- If you choose to use one, consider which one to use based on
context: Don't decide by “what is hot” or “what I know”


Karl.

 

[David Mark]

Richard Cornford wrote: [snip]

The "Potential cons" list:-
- Does not mention that the libraries are rarely actually cross-
browser (but merely support a limited set of brewers, so are actually
little more than an elaboration of the "both browsers" scripts from
the end of the last century).

Ok, I've added a bullet "Rarely supports more than a handfull of browsers"

[snip]

Trade-off: if and what library to use
Potential pros:
- Responsibility of handling most cross-browser concerns are pushed to
the library developers

That's virtually never a pro. Experienced developers know that
complicated, monolithic do-everything-for-everybody scripts are
inappropriate for a language that must be downloaded, runs in a single
thread and must face many disparate environments. It's generally
folly to try and the inexperienced are typically the ones who do.

General-purpose JS libraries and frameworks are also the most
challenging of browser scripting projects, so combined with mostly B
Team contributors, the results are predictably disastrous.

Furthermore, none of the "majors" is capable of supporting progressive
enhancement in any meaningful way. The calling applications have no
idea which methods will work and which will fall on their face. This
precludes any possibility of graceful degradation in hostile or
limited environments.

AFAIK, there is but one (comprehensive) GP library that has come close
to delivering a truly cross-browser (and largely maintenance-free)
experience, while supporting progressive enhancement.

http://www.cinsoft.net/

That being said, I don't recommend telling your students to use it.
They need to learn how to write browser scripts before they start
trying to borrow code from others.

- Common utility functions and reusable components

- One place to go for documentation, and a single community

That's not necessarily a pro either. There are lots of places to go
to find information about JS and browser scripting in general (granted
most of them are very bad). There is but one jQuery documentation
site.

As for community. As Richard noted, the "support" communities are
mostly the blind leading the blind.

Furthermore, it's not always true that there is a single point of
contact. Many of these efforts get fragmented over the years (see
Dojo and Ext JS), even so much as to break their Google search results
by changing domain names (Ext JS and Dojo each did that *twice* at
least).

Potential cons:
- You may not be happy with all the solutions that library developers
have chosen, nor consistency of all APIs

That's an understatement of a disclaimer.

- Rarely supports more than a handfull of browsers

....in their default configurations. Remember that as the developers
typically lack understanding (due to inexperience), they are often
reduced to programming by feel (observing each browser and fiddling
with the code until it appears to work). A familiar refrain when
confronted with incorrect or dubious logic is "show me where it
fails". Clearly that's not programming but pattern arrangement.

- Varying quality of documentation and support

Mostly (and predictably) bad.

- Browser detection requires continous maintainance/upgrades

And it may well fail *today* (in environments unknown to or unobserved
by) the developers. Furthermore, the "upgrades" invariably break
yesterday's browsers, leading them to be lopped off the "supported"
list. Of course, end-users don't read such lists and cannot be
expected to upgrade their browsers in perfect step with the library
developers.

- Monolithic/non-modular libraries will inevitably contain many features
that you won't use

And must be "upgraded" in one go, requiring a reboot of regression
testing. It's a nightmare in practice (again Dojo, Ext JS and the
like are the most extreme examples).

- Libraries will inevitably not contain all you need.

No question there. JQuery has never featured anything that I need
(and likely never will). In fact, it could be argued that a 70K CSS
selector query engine that disagrees with its own QSA shim is a pig in
a poke for anybody these days. There really are no valid arguments
for it. All I ever hear are generalizations like "I use it as a
tool".

Extensibility is
useful.

Extensibility for JS libraries typically involves augmenting
"namespace" objects. You can add properties to objects in any script,
so any script can be considered extensible in this way. Granted, some
take it a step further with additional syntactic sugar, but rarely to
any real positive effect. If anything, it encourages "plug-in"
authors who really shouldn't be writing JS in the first place (let
alone extensions for widely used libraries).

Advice on libraries

* Consider your context
    - General web vs. intranet.
    - Accessibility requirements?
    - Constrained devices? Unknown devices?
    - App-in-a-page or hyper-text document? In between?

* Be aware of the costs and benefits of using a particular library or not
    - Make an informed decision
    - Don't include a library “by default”
    - If you choose to use one, consider which one to use based on
context: Don't decide by “what is hot” or “what I know”

Those are good points, but you need more.

 

[RobG]

Richard Cornford wrote: [...]

"This is considered bad practice, a hack, by many.
   - Unreliable
   - Restricted accessibility
   - Maintenance"

I don't think that "accessibility" has much direct relevance to
browser sniffing. It can be restricted as much without it as with it.

Again, I've used an incorrect word. I mean accessibility to many user
agents - not users. I will rephrase (though I haven't got a concise word
now...)

The use of the term "accessibility" to mean the quality of user
interaction is a misnomer, it should never have come into popular use.
What is meant is usability: that is, how well users can use a site.
The phrase you are looking for is "restricted usability", with the
implication that it is due to dysfunctional, inoperable or unavailable
user interface features that prevent suitable access to the data.

Consider a blind user whose screen reader is befuddled by text loaded
by XHR that is positioned in an appropriate spatial location in a
page, but does not sit in a logical place in the DOM. The screen
reader may well read it out of sequence so it is heard in the wrong
context. The user has accessed the data just fine, but they have
difficulty comprehending it because of awkard or inappropriate
presentation (i.e. the interface sucks).

In another case, a user might access the correct URI but because theu
are unable to cause an appropriate event to occur (say initiate a
hover event when using a touch interface or a click if using a
keyboard) in order to make information appear on the screen, then they
have a usability issue. They may have accessed the data, or at least
the correct URI, they just can't get it to display the information.

If, on the other hand, they access the URI but their internet
connection is too slow and the page times out, they have an
accessibility issue - they can't *get* to the information (or it can't
get to them).

However, I think I'm pissing in the wind on this one. :-(

[...]

Ok, the IE example should suffice to prove the point.

The Safari example shows that host objects can be infuriatingly
inconsistent even in browsers that claim to be more standards
compliant than the others (it just depends on what standard you happen
to be using for which behaviour).

 

[Karl Tikjøb Krukow]

The Safari example shows that host objects can be infuriatingly
inconsistent even in browsers that claim to be more standards
compliant than the others (it just depends on what standard you happen
to be using for which behaviour).

Agreed, there is value in known that it's not "just IE".

I'll keep the document.all Safari example.

Thanks,
Karl.

 

[Karl Tikjøb Krukow]

Richard Cornford wrote: [snip]
The "Potential cons" list:-

- Does not mention that the libraries are rarely actually cross-
browser (but merely support a limited set of brewers, so are actually
little more than an elaboration of the "both browsers" scripts from
the end of the last century).

Ok, I've added a bullet "Rarely supports more than a handfull of browsers"

[snip]

Trade-off: if and what library to use
Potential pros:
- Responsibility of handling most cross-browser concerns are pushed to
the library developers

That's virtually never a pro. Experienced developers know that
complicated, monolithic do-everything-for-everybody scripts are
inappropriate for a language that must be downloaded, runs in a single
thread and must face many disparate environments. It's generally
folly to try and the inexperienced are typically the ones who do.

General-purpose JS libraries and frameworks are also the most
challenging of browser scripting projects, so combined with mostly B
Team contributors, the results are predictably disastrous.

Furthermore, none of the "majors" is capable of supporting progressive
enhancement in any meaningful way. The calling applications have no
idea which methods will work and which will fall on their face. This
precludes any possibility of graceful degradation in hostile or
limited environments.

It was written as a "potential pro"

In an ideal scenario, pushing this responsibility to an experienced
cross-browser developer would be a pro. Obviously, when it is not
handled appropriately, it becomes a con: "You may not be happy with all
the solutions that library developers have chosen, nor consistency of
all APIs".

AFAIK, there is but one (comprehensive) GP library that has come close
to delivering a truly cross-browser (and largely maintenance-free)
experience, while supporting progressive enhancement.

http://www.cinsoft.net/

That being said, I don't recommend telling your students to use it.
They need to learn how to write browser scripts before they start
trying to borrow code from others.

Yes, I mention "My Library" as a notable exception (a long with Fork and
APE, but they don't look as comprehensive nor maintained).

Hopefully, by the end of the course they will be able to comprehend why
code such as "My Library" is written as it is. Hopefully they will
understand the general principles and techniques, albeit they will not
have extensive knowledge of various bugs and quirks of particular
browsers. I won't recommend any particular library: hopefully they will
be able to make an informed decision on their own.

At least that is the goal.

That's not necessarily a pro either. There are lots of places to go
to find information about JS and browser scripting in general (granted
most of them are very bad). There is but one jQuery documentation
site.

As for community. As Richard noted, the "support" communities are
mostly the blind leading the blind.

Again, a "potential" pro. At the course, I will discuss the warning that
Richard and yourself are giving.

Furthermore, it's not always true that there is a single point of
contact. Many of these efforts get fragmented over the years (see
Dojo and Ext JS), even so much as to break their Google search results
by changing domain names (Ext JS and Dojo each did that *twice* at
least).

While I agree that it is not always true, usually it is a single (or a
few) points of contact. I think I will keep this bullet.

That's an understatement of a disclaimer.

Yes, I am deliberately not using too strong statements in this
presentation.

[snip]

And it may well fail *today* (in environments unknown to or unobserved
by) the developers. Furthermore, the "upgrades" invariably break
yesterday's browsers, leading them to be lopped off the "supported"
list. Of course, end-users don't read such lists and cannot be
expected to upgrade their browsers in perfect step with the library
developers.

I will include this point explicitly.

And must be "upgraded" in one go, requiring a reboot of regression
testing. It's a nightmare in practice (again Dojo, Ext JS and the
like are the most extreme examples).

Do you mean as opposed to a modular library where you would be able to
upgrade a particular module, keeping other modules in an older version?

That is a good point.

No question there. JQuery has never featured anything that I need
(and likely never will). In fact, it could be argued that a 70K CSS
selector query engine that disagrees with its own QSA shim is a pig in
a poke for anybody these days. There really are no valid arguments
for it. All I ever hear are generalizations like "I use it as a
tool".


Extensibility for JS libraries typically involves augmenting
"namespace" objects. You can add properties to objects in any script,
so any script can be considered extensible in this way. Granted, some
take it a step further with additional syntactic sugar, but rarely to
any real positive effect. If anything, it encourages "plug-in"
authors who really shouldn't be writing JS in the first place (let
alone extensions for widely used libraries).

I guess extensibility and customization is only relevant for "widget"
libraries.

The notion of extensibility that you consider is a property of the
language itself. It is often not sufficient to be practical: I think the
widgets should be designed with the mindset that the user should be able
to easily change certain properties, provided that they still satisfy
the same contract of the widget API.

But I guess it is really just a question of how well-designed it is: if
well designed, extensibility and customization will probably follow.

Those are good points, but you need more.

Would you mind helping me with what additional points I need? (unless
you mean the points discussed in the present post).

Thanks for taking the time.
Karl.

 

[Karl Tikjøb Krukow]

Karl Tikjøb Krukow wrote: [snip]
- Libraries will inevitably not contain all you need.

No question there. JQuery has never featured anything that I need
(and likely never will). In fact, it could be argued that a 70K CSS
selector query engine that disagrees with its own QSA shim is a pig in
a poke for anybody these days. There really are no valid arguments
for it. All I ever hear are generalizations like "I use it as a
tool".

OT: Well, you need jQuery to add numbers

http://www.doxdesk.com/img/updates/20091116-so-large.gif



Karl.

 

[David Mark]

Karl Tikjøb Krukow wrote:
Richard Cornford wrote:
[snip]
The "Potential cons" list:-
- Does not mention that the libraries are rarely actually cross-
browser (but merely support a limited set of brewers, so are actually
little more than an elaboration of the "both browsers" scripts from
the end of the last century).
Ok, I've added a bullet "Rarely supports more than a handfull of browsers"
[snip]
Trade-off: if and what library to use
Potential pros:
- Responsibility of handling most cross-browser concerns are pushed to
the library developers

That's virtually never a pro.  Experienced developers know that
complicated, monolithic do-everything-for-everybody scripts are
inappropriate for a language that must be downloaded, runs in a single
thread and must face many disparate environments.  It's generally
folly to try and the inexperienced are typically the ones who do.

General-purpose JS libraries and frameworks are also the most
challenging of browser scripting projects, so combined with mostly B
Team contributors, the results are predictably disastrous.

Furthermore, none of the "majors" is capable of supporting progressive
enhancement in any meaningful way.  The calling applications have no
idea which methods will work and which will fall on their face.  This
precludes any possibility of graceful degradation in hostile or
limited environments.

It was written as a "potential pro"

Fair enough.

In an ideal scenario, pushing this responsibility to an experienced
cross-browser developer would be a pro.

Absolutely, but as Richard mentioned, the "majors" are not cross-
browser in any sense of the term. I'd be careful with the term "pro"
as well. Just because somebody somewhere may have paid for the
services of a library author, doesn't make them proficient (only
professional).

Obviously, when it is not
handled appropriately, it becomes a con:

And, the sad story is that it has not been handled appropriately by
the "pros" on the other end as they haven't really done what they set
out to do.

"You may not be happy with all

the solutions that library developers have chosen, nor consistency of
all APIs".

True enough. Of course, they may not be experienced enough to make
wise judgements in such matters. In other words, they may be happy as
clams with something like jQuery and not realize that they are
standing on the shoulders of midgets.

Yes, I mention "My Library" as a notable exception (a long with Fork and
APE, but they don't look as comprehensive nor maintained).

Yes, I think Fork "died" years ago (though may well still work as it
is a cross-browser script). APE has never amounted to much AFAIK.

Hopefully, by the end of the course they will be able to comprehend why
code such as "My Library" is written as it is.

That would be helpful.

Hopefully they will
understand the general principles and techniques, albeit they will not
have extensive knowledge of various bugs and quirks of particular
browsers.

Here's the most important point: it doesn't require vast knowledge of
browser quirks to be successful. After all, how could I have known
what IE8 or IE9 would look like back in 2007?

It's about understanding the underlying abstractions, proper feature
detection and testing patterns and solving problems. Memorization (or
prognostication) rarely enter into it.

Granted, when attempting to solve every problem related to browser
scripting for everybody, there will be times when observation of
quirks is required. But it is what you do with those observations is
what determines how far you will go in this business.

I won't recommend any particular library: hopefully they will
be able to make an informed decision on their own.

Be sure to mention the possibility of *not* using a GP library.
That's also an important concept (and is not tantamount to "writing
everything from scratch").

At least that is the goal.

Hey, I salute you for your efforts. The world needs more competent JS
developers. It starts with the kids.

Again, a "potential" pro. At the course, I will discuss the warning that
Richard and yourself are giving.

Good deal.

While I agree that it is not always true, usually it is a single (or a
few) points of contact. I think I will keep this bullet.

Yes, but more importantly, who are they contacting? Programmers or
pattern arrangers?

Yes, I am deliberately not using too strong statements in this
presentation.

Fair enough.

[snip]

And it may well fail *today* (in environments unknown to or unobserved
by) the developers.  Furthermore, the "upgrades" invariably break
yesterday's browsers, leading them to be lopped off the "supported"
list.  Of course, end-users don't read such lists and cannot be
expected to upgrade their browsers in perfect step with the library
developers.

I will include this point explicitly.

Glad to hear it.

Do you mean as opposed to a modular library where you would be able to
upgrade a particular module, keeping other modules in an older version?

That is a good point.

Yes. And it is important to realize that they all claim to be
modular, but (particularly in the case of Dojo and Ext JS) it's
usually all smoke due to interdependencies. For example, Dojo's XHR
module requires its (highly dubious) query module. What does XHR have
to do with CSS selector queries?

I guess extensibility and customization is only relevant for "widget"
libraries.

Yes, it's more relevant for those. And note that the "widget"
frameworks are often castles built on top of swamps. In other words,
they are the results of developers getting way ahead of themselves. I
can't name one such framework that is not completely execrable. Dojo,
YUI, Ext JS, Cappuccino, SproutCore, qooxdoo, etc. are all ill-advised
and unsuccessful attempts to make every control look the same in every
browser and chop off the browser's built-in layout mechanisms to be
replaced slowly and painfully with single-threaded scripts that fail
miserably (when compared with what they sought to replace) even in
their "supported" browsers. See Richard's comments about qooxdoo's
layout and widget scripts in a recent thread.

The notion of extensibility that you consider is a property of the
language itself. It is often not sufficient to be practical: I think the
widgets should be designed with the mindset that the user should be able
to easily change certain properties, provided that they still satisfy
the same contract of the widget API.

Certainly. Unfortunately, the majors all go way too far with this,
often requiring a half-dozen levels of inheritance and tons of nested
DIV's to create the simplest of controls. As a result, they are slow,
bloated and inaccessible in numerous ways (when compared with what
they sought to replace) And whenever HTML5 finally gets here (and is
widely implemented), all of that crap will end up on history's scrap
heap anyway.

But I guess it is really just a question of how well-designed it is: if
well designed, extensibility and customization will probably follow.

Well, even a poor design can allow for massive customization.

Would you mind helping me with what additional points I need?

I wouldn't mind at all. Perhaps tomorrow.

(unless you mean the points discussed in the present post).

I mean those, but certainly there are more.

 

[David Mark]

Karl Tikjøb Krukow wrote: [snip]
- Libraries will inevitably not contain all you need.

No question there.  JQuery has never featured anything that I need
(and likely never will).  In fact, it could be argued that a 70K CSS
selector query engine that disagrees with its own QSA shim is a pig in
a poke for anybody these days.  There really are no valid arguments
for it.  All I ever hear are generalizations like "I use it as a
tool".

OT: Well, you need jQuery to add numbers

http://www.doxdesk.com/img/updates/20091116-so-large.gif

Good one, Karl.

 

[Ry Nohryb]

Additional questions on attribution:

- Did Cornford or Crockford invent the module pattern?

I used to doubt it before, but when you dig into the c.l.js. archive
starting @ the beginning of 2003 you see that he's been -certainly- a
pioneer of that pattern. He posted quite often and a bunch of
variations on the topic, and it's obvious that he had the feeling and
excitement of whom is inventing/discovering something different, like
a new and unknown piece of JS programming.

 

[Karl Tikjøb Krukow]

On Jul 27, 2:46 pm, Karl Tikjøb Krukow<[email protected]> wrote:

[snip]
In an ideal scenario, pushing this responsibility to an experienced
cross-browser developer would be a pro.

Absolutely, but as Richard mentioned, the "majors" are not cross-
browser in any sense of the term. I'd be careful with the term "pro"
as well. Just because somebody somewhere may have paid for the
services of a library author, doesn't make them proficient (only
professional).

Oh, I didn't mean "pro" as in professional, I meant as "a point in favor
of"

Anyway, I agree.

And, the sad story is that it has not been handled appropriately by
the "pros" on the other end as they haven't really done what they set
out to do.

"You may not be happy with all

True enough. Of course, they may not be experienced enough to make
wise judgements in such matters. In other words, they may be happy as
clams with something like jQuery and not realize that they are
standing on the shoulders of midgets.

Yes, in this case, the problem is hard. Hopefully with the course they
will get at least some degree of knowledge and experience.

Yes, I think Fork "died" years ago (though may well still work as it
is a cross-browser script). APE has never amounted to much AFAIK.

At least http://forkjavascript.org/ still "works"

That would be helpful.


Here's the most important point: it doesn't require vast knowledge of
browser quirks to be successful. After all, how could I have known
what IE8 or IE9 would look like back in 2007?

It's about understanding the underlying abstractions, proper feature
detection and testing patterns and solving problems. Memorization (or
prognostication) rarely enter into it.

Granted, when attempting to solve every problem related to browser
scripting for everybody, there will be times when observation of
quirks is required. But it is what you do with those observations is
what determines how far you will go in this business.


Be sure to mention the possibility of *not* using a GP library.
That's also an important concept (and is not tantamount to "writing
everything from scratch").

Yes, this is will be an important point. The problem is that getting a
GP library is easy, dropping it in your page is easy; not doing that
takes more work (either you do write part of it from scratch, or you
find a number of good reusable modules suitable for your context).

And, getting a number of reusable modules for the particular context
isn't that easy - i.e. there is no good-reusable-js-modules.org.

More often than not most people go for the "easy" solution. The problem
being that it appears to work on all the browsers you have installed
(yes, in their default configuration .

Another point is that of widgets: with a GP library there is always the
chance that it comes with (almost) just that widget you want, or someone
has written that widget as a "plugin". Again it appears to work just
fine (in all the browsers you have installed, yes, in their default
configuration) - you may not consider "accessibility" (or usability, Rob
, use of keyboard.

In this case, the alternative often is writing it from scratch...
Still looking for quality-js-widgets.org

Anyway, I want to convey the message that using a GP library is not an
automatic default: it comes with a cost. Sometimes that cost is too high.

Hey, I salute you for your efforts. The world needs more competent JS
developers. It starts with the kids.

Thanks At least this should not be "the blind leading the blind", as
you say.

I may not see all that well, but at least I can steer away from the abyss...

[snip]

Yes, but more importantly, who are they contacting? Programmers or
pattern arrangers?

Yes, that is important.
[snip]

Yes. And it is important to realize that they all claim to be
modular, but (particularly in the case of Dojo and Ext JS) it's
usually all smoke due to interdependencies. For example, Dojo's XHR
module requires its (highly dubious) query module. What does XHR have
to do with CSS selector queries?

Yes, part of the course is actually teaching the client the basics of
Ext JS which is used to build "app-in-a-page" things on their intranet
(where they use only IE7+ and FF3+ on windows).

I tried to use the Ext JS "builder" to create a version of the library
that only included the parts we were using: it included almost
everything so much for modularity...
[snip]

Yes, it's more relevant for those. And note that the "widget"
frameworks are often castles built on top of swamps. In other words,
they are the results of developers getting way ahead of themselves. I
can't name one such framework that is not completely execrable. Dojo,
YUI, Ext JS, Cappuccino, SproutCore, qooxdoo, etc. are all ill-advised
and unsuccessful attempts to make every control look the same in every
browser and chop off the browser's built-in layout mechanisms to be
replaced slowly and painfully with single-threaded scripts that fail
miserably (when compared with what they sought to replace) even in
their "supported" browsers.

But I still have hopes that it will be possible to build those castles
on a better foundation, some day. The client wants castles in browsers.

See Richard's comments about qooxdoo's
layout and widget scripts in a recent thread.

I will.

Certainly. Unfortunately, the majors all go way too far with this,
often requiring a half-dozen levels of inheritance and tons of nested
DIV's to create the simplest of controls. As a result, they are slow,
bloated and inaccessible in numerous ways (when compared with what
they sought to replace) And whenever HTML5 finally gets here (and is
widely implemented), all of that crap will end up on history's scrap
heap anyway.

You are speaking about Ext JS again, aren't you?

Yes, HTML5 would remove the need for many, but probably not all, of
those "widgets". And I guess canvas would help too.

Well, even a poor design can allow for massive customization.

Yes, I meant the other implication: a good design would imply at least
some degree of customization.

I wouldn't mind at all. Perhaps tomorrow.

Thanks. Looking forward to it.

Karl.

 

[Karl Tikjøb Krukow]

I am preparing an introductory course on JavaScript for the place I work
at. As part of the course, I would like present some of the common
knowledge and generally accepted advice of this group, since it is not
commonly known and it should guide them in the right direction.

(A small) part of this is on general purpose libraries. I've exported
the slides as a set of html documents which can be found here:

<http://higher-order.net/courses/05-js-libraries.html>

I would appreciate feedback from the group. Remember that this is an
introductory course to it should be kept to basics and generally
accepted statements.

I've had so much interesting feedback that I've chosen to publish also
the slides on the "basic language constructs" hoping for interest and
advice.

<http://higher-order.net/courses/02/02_basic_language_constructs.html>


Karl.

 

[Karl Tikjøb Krukow]

On 29/07/10 07.04, Karl Tikjøb Krukow wrote:
[snip]

I've had so much interesting feedback that I've chosen to publish
also the slides on the "basic language constructs" hoping for
interest and advice.

OT: do you see my lines wrapping at 72 chars? I've just upgraded to the
newest thunderbird (from the 2.x branch to 3.x) and it seems to have
dropped support for wrapping lines

Karl.