Essential jQUERY

Recently, I picked up the bare essentials in jQuery from the book, jQUERY Visual Quickstart Guide by Steven Holzner, Peachpit Press, 2009.

However, a word of warning: the book is somewhat badly edited, and there is no corrected edition (still as of this writing).

From the core jQuery source code, this page also is useful. Here are my brief notes:

JQuery refers to a certain syntax $(thing) for any thing as 'jQuery-wrapping'.

The keyword $ is an alias for jquery. Both are used in the following ways:

• $(function)  –  Append a function to the list to be run when the document is ready: a shortcut for $(document).ready(function).


• $(CSS-selector-string)  –  Select some nodes in the document.


• $(HTML-string)  –  Create HTML for insertion.


• $(DOM-node)  –  Like saying simply DOM-node, but change the value of this and set context (an attribute used by jQuery). Examples are:
  •   $(document)  –  The document.
    
  •   $(this)  –  this.


• $.method  –  (This one has a dot and no parentheses.) Run a utility method.

The jQuery methods selected for explanation in the book are:

• Methods on jQuery-wrapped collections of HTML elements:
  
• addClass,  after,  alt,  animate,  append,  attr,  before,  bind,  clone,  css,  each,  (event binder methods),  fadeIn,  fadeOut,  fadeTo,  height,  hide,  hover,  html,  is,  (jQuery-UI methods),  length,  load,  one,  serializeArray,  show,  size,  slice,  slideDown,  slideToggle,  slideUp,  text,  toggle,  toggleClass,  unbind,  val,  width,  wrap


• Event binder methods:
  
• Keyboard   –   keydown,  keypress,  keyup


• Mouse   –   mousedown,  mouseenter,  mouseleave,  mousemove,  mouseout,  mouseover,  mouseup


• The rest   –   beforeunload,  blur,  change,  click,  dblclick,  error,  focus,  load,  resize,  scroll,  select,  submit,  unload


• jQuery-UI methods:
  
• accordian,  datepicker,  dialog,  progressbar,  slider,  tabs


• Methods on jQuery-wrapped HTML strings:
  
• insertAfter,  insertBefore


• Utility methods:
  
• ajax,  browser,  each,  get,  grep,  inArray,  isArray,  isFunction,  makeArray,  map,  post,  support,  trim,  unique

Copyright (c) 2013 Mark D. Blackwell.

Meetup authentication & email addresses

As part of its OAuth authentication process with other apps, Meetup doesn't provide email addresses of its users. (I refer to this official Meetup forum question, and to this page in the Meetup API docs—search the page for 'email'.)

Twitter doesn't provide email addresses either. However, Meetup seems nicer than Twitter.

People use multiple Twitter accounts (I know some who do). But people don't use multiple Meetup accounts (at least supposedly not).

When registering new users through this difficult class of OAuth authentication providers (those which don't supply an email address) one might ask each new user directly for some email address, or might not. Requesting this is normally recommended.

If an app uses Meetup authentication (and it doesn't request and confirm an email address during user registration), and uses another form of authentication also (even added later) then there's no way to identify the same user, if or when they sign on by a different way.

So Meetup authentication (without email) is only good if the app is forever limited to using Meetup authentication alone. With that permanent limitation, in such an app, nobody (mysteriously) will run into the problem of having more than one account.

Of course, having Meetup as the single method of authentication is useful, reasonably, only to apps which are already limited to Meetup users.

Keeping the UI simple (by not requesting an email address when people register) means the app might never have email addresses. But that might be okay if an app uses Meetup authentication alone, forever.

Then one need not bother people with asking for their email address when they first use an app. The ease of that emotional UX moment when new customers are forming their first impression of an app (and making their initial commitment to it), from the standpoint of building a customer base—depending on the app—could be considered more important than ever knowing their email addresses.

BTW, omniauth-meetup is a good gem for doing Meetup authentication in Rails.

Copyright (c) 2013 Mark D. Blackwell.

Flat UI and Twitter Bootstrap "Mobile First" for Rails

Designmodo's announcement for their free Flat UI (which uses Sass) mentions plans (in the discussion) to release a pay version containing LESS code. And an issue on their Flat UI gem floats a suggestion of possibly porting it to LESS.

Darthdeus' gem flat-ui-rails contains Flat UI precompiled to CSS with no LESS code.

Whether Flat UI will continue to be maintained and useful for Rails doesn't relate to Darthdeus' trivially easy to maintain gem but therefore instead to Designmodo's free Flat UI product itself. So far, BTW, their Pro version seems to be vaporware.

There is a rumor Twitter Bootstrap version 3 "Mobile first" will have a flatter UI, but that's only temporary (for development purposes) according to this article.

Web searching revealed no sign how Designmodo's Flat UI might be affected by Twitter's new "Mobile first" initiative otherwise.

Copyright (c) 2013 Mark D. Blackwell.

StackExchange family (including Stackoverflow) doesn't care about signout

I again registered a test account for 'Log in with Stack Exchange'.

Disappointingly, after logging out of every (SE family) site, it still lets me log in again merely by button clicks, while I type nothing.

After more than a year, clearly the managers of the Stack Exchange network family of websites don't give a hoot about protecting users of shared computers with a truly effective signout.

What if some rude person at a party click-logged into and deleted someone's account, thus trashing their vast accumulation of reputation?

Copyright (c) 2013 Mark D. Blackwell.

Fix spurious XP warning 'firewall not started', howto

Spuriously the last few days, booting my XP computer, I've been warned my firewall is down (in a yellow message bubble). Microsoft's Security Center software (running locally) says, "Microsoft Security Essentials is turned off." The message is not transient, either.

However, real-time protection is running just fine!

Running Microsoft's WMIDiag diagnostic tool didn't help, but web searching the message gave me this procedure (to rebuild a corrupted WMI repository—when prompted, answer yes):

> cd %windir%\system32\wbem
> net stop winmgmt
> dir /ad
> ren Repository Repository.old
> net start winmgmt
> net start "security center"
> firewall.cpl

Then in the General tab, select 'On' to restart Windows Firewall.

If you really want to understand WBEM (mentioned above, Web-Based Enterprise Management, or Microsoft's version: WMI, Windows Management Instrumentation) you can click this humorously easy introduction or web-search it.

Copyright (c) 2013 Mark D. Blackwell.

Thomas Young mass setting open letter

Subject: Thomas Young mass setting by Mark D. Blackwell

TYC Administrator
Thomas Young Centre
The London Centre For Theory And Simulation Of Materials

Dear madam:

Since your website:

http://www.thomasyoungcentre.org/about-tyc/contacts/

indicates you as the first point of contact, I write to announce with pleasure that I have composed a mass setting in honor of your own Thomas Young, the famous polymath.

This entire mass setting was inspired by Thomas Young's list of major thirds in his own Young Temperament (a well-temperament for keyboards). He arranged these thirds in order of increasing size (thus increasing distance from purity). In his design, this order matches the key signatures with increasing numbers of sharps and flats. His temperament (I assume you know) is described here:

http://en.wikipedia.org/w/index.php?title=Young_temperament&oldid=505261244

To be more explicit, the chord roots in this mass setting exactly follow Thomas Young's ordered sequence (or otherwise relate to it): C, G, F, D, Bb, A, Eb, E, Ab, B, Db, Gb.

You might find it amusing to inform your membership of this connection to your namesake, perhaps in a note in a publication. At least, I hope so!

The "Thomas Young" mass setting can be heard here (click the icons which depict two notes on a staff):

http://www.bakerartistawards.org/nominations/view/MarkDBlackwell/#project_10581_detail

Copyright (c) 2013 Mark D. Blackwell.

Compositions self-nominated to Baker Artist Awards

I nominated my musical compositions for consideration for the various local Baker artist awards and grants (of Baltimore) by adding a page on their site just now.

Please consider looking! As you know, comments are love (there, as ever).   :-)

Copyright (c) 2013 Mark D. Blackwell.

SATB sheet music from Mutopia

I have prepared a selection (twenty-nine numbers) of SATB sheet music, starting from Mutopia's search filter in the vocal category.

All have lyrics in English, Latin, or Spanish (and some French, German, and Italian) in the staff (as opposed to being separately printed).

They are not filtered for quality, nor for content type (such as religious).

They are engraved using the beautiful Lilypond, as everything is on Mutupia.

• Abendruhe—W. A. Mozart (1756–1791)
• Al mormorar de' liquidi cristalli, madrigale a 6 voci—G. Gastoldi (1556–1622)
• Alas! and did my savior bleed?—J. K. Banks (1987–)
• All my heart this night rejoices—C. E. Horsley (1822–1876)
• Ave Maria—P. Benoit (1834–1901)
• Beatus vir—C. Monteverdi (1567–1643)
• Caligaverunt—J. Naujalis (1869–1934)
• Come again—J. Dowland (1563–1626)
• Dies irae—W. A. Mozart (1756–1791)
• Dolcissima mia vita—C. Gesualdo (1566–1613)
• El grillo—J. des Prés (c.1440–1521)
• Es ist ein ros’ entsprungen (Anonymous)
• Fairest isle—H. Purcell (1658–1695)
• Glory to god in the highest—G. B. Pergolesi (1710–1736)
• Magnificat—P. Benoit (1834–1901)
• Musiche per la maddalena—C. Monteverdi (1567–1643)
• O how amiable are thy dwellings—T. Weelkes (1576–1623)
• O nata lux de lumine—T. Tallis (1510–1585)
• Popule meus—J. Naujalis (1869–1934)
• Receive the body of Christ—D. Johnson (?–)
• Sestina—C. Monteverdi (1567–1643)
• Sibylla samia—O. de Lassus (1530 or 1532–1594)
• Silver swan, the—O. Gibbons (1583–1625)
• T'amo mia vita—C. Monteverdi (1567–1643)
• Tantum ergo sacramentum—F. J. Haydn (1732–1809)
• Tantum ergo—F. Schubert (1797–1828)
• To hope—S. Magnenat (1980–)
• Trust and obey—D. B. Towner (1833–1896)
• Unquiet thoughts—J. Dowland (1563–1626)

Copyright (c) 2013 Mark D. Blackwell.

Node.js event loop does not poll

Node.js uses a well-known event loop, but does it work by polling? Some have that impression.

An event loop¹ works by requesting its events from a message pump (per Wikipedia).

Here's how the event loop is implemented: 'Internally, node.js relies on libev to provide the event loop, which is supplemented by libeio[,] which uses pooled threads to provide asynchronous I/O.'².

Here's Wikipedia's article on polling³ and another definition⁴.

Now, 'poll' is a system call which asks Unix to check a set of file descriptors:

'poll, ppoll - wait for some event on a file descriptor...If none of the events requested (and no error) has occurred for any of the file descriptors, then poll() blocks until one of the events occurs.'⁵

Possibly, the system call's name may have misled people into thinking a userland program is doing polling. Nevertheless, when the 'poll' (Unix system call) is invoked, this is not polling in itself.

Hypothetically, in order to get information from a message pump, an event loop could employ the Unix system call 'poll' to check a file descriptor, to which the message pump would write events.

Ultimately, this may be the source of the conceptual confusion here, or it may be caused by the fact that (actual) polling is the easiest method to think of, when programming.

For our case in particular, if an event loop calls Unix 'poll', this is not an instance of the event loop polling anything. Neither node.js, nor any event loop, but only Unix, polls the file descriptors (if indeed it even really does, anymore).

Anyway, an event loop, such as node.js's, does not poll its message pump. Instead, it merely makes a (blocking) request to it. Calling just any request 'polling' pollutes the meaning of the word (and that may be happening here.)

tl;dr – So, let's try anymore not to say that node.js is polling its events—okay? Instead, let's simply say that node.js waits for its events. (A lost cause, I know—but at least I've said it.)

1 http://en.wikipedia.org/wiki/Event_loop
2 http://blog.mixu.net/2011/02/01/understanding-the-node-js-event-loop/
3 http://en.wikipedia.org/wiki/Polling_%28computer_science%29
4 http://whatis.techtarget.com/definition/polling
5 http://linux.die.net/man/2/poll

Copyright (c) 2012 Mark D. Blackwell.

Install Opa language on 32-bit Debian squeeze, howto

The coolest feature of the Opa web programming language is that it automatically divides developers' programs into server and client sides, compiling to JavaScript.

Though the Opa compiler (as of this writing) doesn't have a 32-bit binary for Windows, I got it working in an easy way on (32-bit) Debian squeeze, after upgrading my nodejs installation.

Following Opa's instructions to install as a user (under the heading, Other Linux Distribution), I downloaded and ran their 32-bit Linux self-extracting package. When prompted, I chose to install it into ~/progra/mlstate-opa.

Then, after navigating to A tour of Opa in the sidebar, under the heading, Easy Workflow, I found and typed into a file, 'hello.opa' their sample program. The command:

$ opa hello.opa --

errored out, asking for more npm modules to be installed.

Rather than exactly following their suggested course of action, which would have installed node modules to root-owned directories, I typed:

$ npm install mongodb formidable nodemailer simplesmtp imap

After that the compiler worked just fine.

Copyright (c) 2012 Mark D. Blackwell.