17 entries tagged
javascript
A new on-line quiz for all you people out there:
How tall are you?
I have added Javascript code to the page so that it works
out the answer for you (if you have Javascript disabled in
your browser you should still be able to read the page, you just
won’t get any help counting your answers). I have
also taken the liberty of decorating the page with
SVG doodles. This may or may
not give your browser conniptions...:-)
SVG notes.
I have tested it on Mozilla on Linux sans SVG; the fall-back PNG
images display correctly. MSIE 4.0 on Windows NT with Adobe SVG
plug-in 3.0 displays the SVG correctly—you can zoom in and
view SVG in another window etc. And at work I verified
(in MSIE 5½) you can print the page, in
which case the pictures are rendered with the printer’s
resolution, not the screen’s. Cool! MSIE/Mac 5.0 on my
decrepit Performa sort of goes loopy while the SVG files
download, then each doodle turns blank when you scroll the page;
frobbing the the zoom or quality causes the image to redisplay.
Weird.
Before going in to work today I have managed to fix one of the
JavaScript problems (it causes MSIE to report ‘one error
on page’), but only half-fixed the other (which causes
artists’ names with links to vanish when you cycle through
the panels). In the latter case, the name no longer vanishes,
but, alas! the link does.
I think need a JavaScript
debugger—in other words, to install Mozilla on my
PowerBook (the only computer I own with enough welly for
Mozilla). Ho hum.
I have added JavaScript to the upload form Picky Picky Game on
caption.org to optionally remember your details for next
time (using a cookie). This way you don’t have to enter
your URL each time you upload a new panel.
Debugging JavaScript without a JavaScript debugger is a real
pain in the arse, and illustrates how subtle aspects of language
design affect the experience of working in that language. There
is one crucial difference between Python and JavaScript. In
Python, a variable is implicitly created the first time you
assign to it; in JavaScript, it is created the first time you
refer to it. This means that the following fragment is valid
JavaScript:
var cookieHeader = this.$document.cookie;
var m = myRegexp.exec(cookiesHeader);
if (m) {
... use the match info to process the cookies ...
}
The equivalent Python looks like this:
cookieHeader = self._document.cookie
m = myRegexp.search(cookiesHeader)
if m:
... use the match info to process the cookies ...
In the JavaScript version, the regexp (used to extract one
cookie from the Cookies header) will mysteriously never match
and you will spend ages scrutinizing the regexp and flipping
though the documentation on what is and is not valid regexp
syntax in JavaScript. In Python you will get an error message
telling you that the variable cookiesHeader is
referred to before it is assigned to—and immediately
realise its name is misspelled in the second line.
The tedious thing about testing the ‘remember me’
option is that it involves repeatedly doing the very thing it is
supposed to be saving me from: entering my URL and details
on the picture-upload form. Luckily I was testing on Safari,
which has a form auto-completion feature that makes repeatedly
filling in the form less annoying—but which also makes the
‘Remember me’ feature almost entirely redundant
;-)
The image-cycling feature of the
Picky Picky Game
prototype depends on using JavaScript to load images. If
you click on the Cycle button before the images have been
prloaded, then nothing visible happens—it appears to have
failed. There is no way for the user to see whether the images
have loaded or not. I have attempted to add such an indication,
only to be thwarted by what appear to be bugs in the web
browsers I have tried it on.
Read more
The
SVG-powered simulated deal now works on Safari. In the
end I achieved this by using the special attribute that
signals to Adobe that it should use its own JavaScript engine,
not its host’s (in this case, Safari’s).
I have also belatedly switched the script to using
document.URL to find its URL rather than the
HTML-style location.search (which fails on Safari
as well).
Read more
Last week I was struggling with Adobe Flash development, wishing that my
recommendation that we drop Flash and spend the programming time on
improving our fall-back HTML+JavaScript version instead had not fallen
on such stony ground. Then on Sunday there was a flurry of articles
speculating that not only is Apple’s iPhone missing an implementation of
Flash, but Apple might not intend to add one---and might even want to
start pushing web developers towards alternatives like HTML+JavaScript.
Read more
This weekend—over and above working on our ongoing greenhouse-erection
project—I have created a simple explorer for CouchDb servers that
for want of a better name I have called Hello.
Read more
A couple of weekends ago I decided to take up one of the Work
Items for CouchDb: write a client for the server that runs as
JavaScript in the user’s browser, Ajax-style. As someone whose day job
is writing web sites using Microsoft ASP.NET and Microsoft SQL Server,
writing an application in plain JavaScript+HTML comes as a refreshing
change.
Read more
I created an SVG-powered jigsaw app for the 10K Apart contest. To get
it under 10K I had to squash the JavaScript and CSS files down as much
as possible (within the rules).
Read more
I created an SVG-powered jigsaw app for the 10K Apart
contest. While the judges ponder their decision, just for fun I have
created it its own web site, jigsawr.org.
Read more
I created an SVG-powered jigsaw app for the 10K Apart
contest.
Just for fun, here’s a bookmarklet you can use to create a jigsaw from any page.
Read more
The plan with Kanbo is to skip having priority fields for tasks and instead to
just let the cards be rearranged in whatever order you like. This poses a
couple of technical challenges: first, the only nice user interface for
rearranging things is drag-and-drop, and second, relational databases are
notoriously wedded to the idea that entities are an unordered set, so how
should the order be represented?
Read more
I have been neglecting Kanbo while job-seeking and doing freelance jobs,
but today I did one token update: I added a bookmarklet on the details
page of a board that can be used as a shorthand to add a card to that
board.
Read more
I wanted to have a little React project of my own to play with, so I have
React-ified the entry navigator links on my blog pages. This is partly to in
order to get some practice in with this different way of approaching
JavaScript interactivity.
Read more
After reading the text version of a talk by Maciej Cegłowski
titled The Web Obesity Epidemic I felt pretty smug because I
thought I had redesigned my blog on reasonably minimal lines. Then I
checked and was chagrined to discover a recent entry page was
1.01 MB compared with Maciej Cegłowski’s entire talk weighing
in at slightly less than 1 MB. I decided to try to work out
where I went wrong.
Read more
I figured that the first step in fiddling with the JavaScript code I use on my navigation widget will be to convert it
in to a more fashionable build system, such as Webpack. Can I reduce the bandwidth usage of my pages thereby?
Read more
I have started building a toy web application to give myself
something to try out some of these newfangled JavaScript frameworks
like React and Redux.
Read more
