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javascript_howto thread: Problem: bad syncronizing in Javascript...


Message #1 by "Sten Hougaard" <STG@e...> on Thu, 12 Sep 2002 13:41:32 +0200
Hi,

The problem occures within a commercial soloution, I am
sorry I cannot show you any code.

It is an advanced soloution which pushes the use of client
based programming to the limit (over? Ofcause not! :-).

Simply put:

[SERVER PART] <=> [CLIENT SIDE]

[CLIENT SIDE]:
  "APPLET" <=> "Javascript" <=> "DOM/DHTML" <=> User...

The problem seems to occur when the Applet execuses some
communication to/from the server. It seems to halt the
javascript. This would not be a problem, if I could trust
certain states of some DOM/DHTML properties.

Example:

a) JS: "Please change URL of an image"
b) JS: "wait for the READYSTATE of the image to be "ready""
c) APPLET: Do some action...
d) JS: "Done... Reset the URL of  an image"

YOU read it from a to d, right?
So should the JS-script engine do, right?
NO! It does not!

The step "b" is "lying" - it says "the image is ready", but actually
it is not rendered yet on the screen! My program might show
a "please wait" message in "a" and then do the heavy Applet stuff
after that. But in fact the "please wait" will never show!

Reason: The applet is started before the readystate of the
image is actually "ready" - JS supplies with me an false
state in line "b"... :-/

Hope this explains the (rather) complex situation for which I ask
for help :-)

Cheers

Mr. Sten Hougaard


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