Javascript looses mind on resize event

Howard

I am having a problem that is driving me crazy and I am whits end. I am
hoping that someone here can help me. I have a client server application
where the client is drawing a progressive bar graph based on data
retrieved from the server once a second. The basic loop looks like this;

</HEAD>
<script language="JavaS cript1.2">

var nodedatareq;
function buildGraphs() {

document.writel n("<BODY>");

// build graphs and add them

document.writel n("</BODY>");

window.addEvent Listener("resiz e",resizeEventH andler, false);
}

function initXMLHTTPRequ est() {
var xreq= null
if( window.XMLHttpR equest ) {
xreq= new XMLHttpRequest( )
} else if(window.Activ eXObject) {
xreq= new ActiveXObject(" Microsoft.XMLHT TP")
}
return xreq
}

function sendNodeRequest ()
{
var mnodedataod="PO ST";
nodedatareq = initXMLHTTPRequ est();
if( nodedatareq ) {
nodedataParam = "nodedata=" + escape(1)
nodedatareq.onr eadystatechange =nodedataHandle r
nodedatareq.ope n(mnodedataod,s erverURL,true)
nodedatareq.set RequestHeader(" Content-Type",
"applicatio n/x-www-form-urlencoded")
nodedatareq.sen d(nodedataParam )
}
}

function nodedataHandler () {

var ready= nodedatareq.rea dyState
var respStr=null
var index
if( ready == READY_STATE_COM PLETE ) {
respStr=nodedat areq.responseTe xt

// plot data

timer = setTimeout(send NodeRequest, 1000)
}
}
function resizeEventHand ler(target, e)
{
// do nothing
}

buidGraphs()
timer = setTimeout(send NodeRequest, 1000)
</script>

This works fine advancing the graphs and looping until I resize the
window. Once I do that the first time it reenters sendNodeRequest () I
get an error that initXMLHTTPRequ est is undefined. I tried inlining the
code for initXMLHTTPRequ est into sendNodeRequest but then it complains
thay nodedatareq is undefined. It is as if it has completely lost all of
its history and has no context or scope.

I have tried using

window.onresize = function(e) {resizeEventHan dler(e);};

instead of window.addEvent Listener. I tried

window.onresize = function(e) {resizing = 1;};

so it didn't have to call a function, but that had the same results.

I also tried putting the call to window.addEvent Listener before the call
to buildGraphs. Then it didn't die but the event was not seviced either.

Anyone have any suggestions?

Thanks

Howard

Dec 16 '06 #1

Subscribe Reply

2751

pcx99

Howard wrote:

If you don't return false in your event handlers, the browsers will
quite cheerfully continue in their default behavior, the kind which is
driving you crazy. Once you start returning false they will do what you
ask and no more.

window.onresize = function(e) {resizeEventHan dler(e);};

instead of window.addEvent Listener. I tried

window.onresize = function(e) {resizing = 1;};

so it didn't have to call a function, but that had the same results.

window.onresize = function(e) {resizeEventHan dler(e); return false};
window.onresize = function(e) {resizing = 1; return false};

function resizeEventHand ler(target, e)
{
// do nothing and fail, return false for teh win
return false;
}

Note that not all browsers pass e.

if (e == null) { e = window.event; }

will make the code more cross browser compliant.

No idea why a resize event would trip your application up, not enough
information was supplied in the pseudo code. So there's no guarantee
this will work.

G'luck.

--
http://www.hunlock.com -- Musings in Javascript, CSS.
$FA

Dec 16 '06 #2

Richard Cornford

Howard wrote:

I am having a problem that is driving me crazy and I am
whits end. I am hoping that someone here can help me. I
have a client server application where the client is
drawing a progressive bar graph based on data retrieved
from the server once a second. The basic loop looks
like this;

</HEAD>
<script language="JavaS cript1.2">

^^^
This is silly in a script that requires the use of an XML HTTP request
object. You certainly do not want browsers that support the aberrant
type-conversion and alternative syntax of JavaScript 1.2 to actually
employ that language version.

>
var nodedatareq;
function buildGraphs() {

document.writel n("<BODY>");

// build graphs and add them

document.writel n("</BODY>");

window.addEvent Listener("resiz e",resizeEventH andler, false);
}

<snip>

This works fine advancing the graphs and looping until I
resize the window. Once I do that the first time it reenters
sendNodeRequest () I get an error that initXMLHTTPRequ est is
undefined. I tried inlining the code for initXMLHTTPRequ est
into sendNodeRequest but then it complains thay nodedatareq
is undefined. It is as if it has completely lost all of its
history and has no context or scope.

<snip>

That is precisely what has happened. If you use -document.write - or
document.writel n - after the original document has loaded you are
re-opening the document, removing all of its existing contents, and
associated script functions and variables, and replacing the document
from scratch. You may not be calling either of the - write - methods
after the first loading of the document (though you also may as the
request is asynchronous and the time for the response to start will be
influenced by many factors, including network traffic), but as soon as
you re-size handler re-calls the method that does the wiring the current
document, and associated scripts, are removed and replaced.

Richard.

Dec 16 '06 #3

Lee

Howard said:

>
I am having a problem that is driving me crazy and I am whits end.

You're at the end of the smallest part imaginable because
Javscript seems to be allowing it's mind to run loose?
--

Dec 16 '06 #4

Howard

Thank you for your response

Richard Cornford wrote:

Howard wrote:

<snip>

></HEAD>
<script language="JavaS cript1.2">
^^^
This is silly in a script that requires the use of an XML HTTP request
object. You certainly do not want browsers that support the aberrant
type-conversion and alternative syntax of JavaScript 1.2 to actually
employ that language version.

So, I am better off just using <scriptor some other version

<snip>

but as soon as
you re-size handler re-calls the method that does the wiring the current
document, and associated scripts, are removed and replaced.

I am not sure what you are saying here (a function of my lack of
knowledge I am sure). Is the location of my setting the callback the
problem or is the act of having a callback on the window object the
problem? I have tried moving the setting of the callback to other
locations in the script outside the <body>...</bodysection. If I move
the setting to before it, the callback never gets called. If I move it
after I get the same undefined. If setting the callback on the window
object is the problem, where is a better place to put it?

Thanks again

Howard

>
Richard.

Dec 18 '06 #5

Lee

Howard said:

>
Thank you for your response

Richard Cornford wrote:
>Howard wrote:

<snip>

>></HEAD>
<script language="JavaS cript1.2">
^^^
This is silly in a script that requires the use of an XML HTTP request
object. You certainly do not want browsers that support the aberrant
type-conversion and alternative syntax of JavaScript 1.2 to actually
employ that language version.

So, I am better off just using <scriptor some other version

<snip>

>but as soon as
you re-size handler re-calls the method that does the wiring the current
document, and associated scripts, are removed and replaced.

I am not sure what you are saying here (a function of my lack of
knowledge I am sure). Is the location of my setting the callback the
problem or is the act of having a callback on the window object the
problem?

Your script tag should be:
<script type="text/javascript">

The problem is that you use document.write after the page has loaded.
The first thing document.write( ) does is to clear the page memory.
You need to choose another method of updating the page, such as
changing the innerHTML property of some component.
--

Dec 18 '06 #6

Howard

Got it, and fixed it. Thanks

Howard
Lee wrote:

Howard said:
>Thank you for your response

Richard Cornford wrote:
>>Howard wrote:
<snip>

>>></HEAD>
<script language="JavaS cript1.2">
^^^
This is silly in a script that requires the use of an XML HTTP request
object. You certainly do not want browsers that support the aberrant
type-conversion and alternative syntax of JavaScript 1.2 to actually
employ that language version.
So, I am better off just using <scriptor some other version

<snip>

>>but as soon as
you re-size handler re-calls the method that does the wiring the current
document, and associated scripts, are removed and replaced.
I am not sure what you are saying here (a function of my lack of
knowledge I am sure). Is the location of my setting the callback the
problem or is the act of having a callback on the window object the
problem?

Your script tag should be:
<script type="text/javascript">

The problem is that you use document.write after the page has loaded.
The first thing document.write( ) does is to clear the page memory.
You need to choose another method of updating the page, such as
changing the innerHTML property of some component.

Dec 19 '06 #7

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