problem with reading XML-Document in Firefox

Re XML, Javascript, IE, Firefox
Hi,
I have a very simple & small XML file (only 7 variables). The code works for IE, but not for Firefox. I've search around and found lots of alternatives, but all different and mostly way above my competance level to understand (ieg Ajax;-(). Could someone give me some guidance please. - thanks

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    var xmlDoc;

// Code for IE

if (window.ActiveXObject)

{

    document.write("IE detected<br>");

    xmlDoc=new ActiveXObject("Microsoft.XMLDOM");

    xmlDoc.async=false;

    xmlDoc.load("readings.xml");

    var save = xmlDoc.getElementsByTagName("save")[0].childNodes[0].nodeValue;

// ... followed by a similar line for the 6 other input variables.

}

// Code for Mozilla, Firefox, Opera, etc.

else if (document.implementation && document.implementation.createDocument)

{

    document.write("Firefox detected<br>");

    xmlDoc=document.implementation.createDocument("","",null);

    xmlDoc.load("readings.xml");

    xmlDoc.onload=readxmldata;  // gives error that onload is not legal!!

    var save = xmlDoc.getElementsByTagName("save")[0].childNodes[0].nodeValue;

// ... followed by a similar line for the 6 other input variables

}

else

{

    alert('Your browser cannot handle this script');   //For TESTING ONLY

}
 
// for testing:

document.write("Save  :" + save + "  <br>");

Sep 14 '07 #1

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2593

pbmods

5,821

Expert 4TB

Heya, Gretsch.

What do you want your code to do? Give an example.
What is your code doing that you don't want it to do? Give an example.
What is your code *not* doing that it is supposed to? Give an example.

Sep 14 '07 #2

Gretsch

Thanks,
I want the code to read in the 7 variables from the XML file and allow me to perform calculations with them. When I use IE it all works fine, but when I use Firefox it prints my "Firefox detected" test msg,(so I know it's getting to the right bit of code) but doesnt print the document.write("Save ;" + save + .... line.

Here's a sample bit of my XML file:

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 <?xml version="1.0" ?>

<meter_readings>                    

<save>    1234000    </save>            

</meter_readings>

My pasted code above just (should) print the variable to the screen for testing, as the rest of the program is the same for all browser and works OK when tested with IE. It's just reading in the variables with Firefox that I have problems with.
Firefox Javascript console just tells me that "The variable "save" is not defined", from which I deduce one of the earlier lines is wrong .... but which?
Thanks for your help.

Sep 15 '07 #3

gits

5,390

Expert Mod 4TB

hi ...

i assume that the xml-doc is not ready at this point where you try to retrieve the values ... have a look here where you might see that you have to retrieve the values onload of the doc ... have a look at the getmessage() function of the example there.

kind regards

Sep 15 '07 #4

Gretsch

Thanks Gits,
When I read your link I thought you had led me to the complete solution; in that my code is in Body, and your suggestion in Head ... but I'm still in trouble.

Your link uses:
document.getElementById("to").innerHTML= xmlDoc.getElementsByTagName("to")[0].childNodes[0].nodeValue;
and html prints the result using 

but I need to perform calcs on the variable, so I'm using (nb. "save" is my 1st variable)
var save = xmlDoc.getElementsByTagName("save")[0].childNodes[0].nodeValue;
but I get the error report "save is not defined.

I include below your links code - with min. needed changes by me.
Could you/someone tell me where I'm going wrong - thanks.

Expand|Select|Wrap|Line Numbers

 <html>

<head>

<script type="text/javascript">

var xmlDoc;

function loadXML()

{

// code for IE

if (window.ActiveXObject)

  {

  xmlDoc=new ActiveXObject("Microsoft.XMLDOM");

  xmlDoc.async=false;

//  xmlDoc.load("note.xml");     //replaced below by my xml file

    xmlDoc.load("meter_readings.xml");

    getmessage();

  }

// code for Mozilla, Firefox, Opera, etc.

else if (document.implementation &&

document.implementation.createDocument)

  {

  xmlDoc=document.implementation.createDocument("","",null);

//  xmlDoc.load("note.xml");     //replaced below by my xml file

    xmlDoc.load("meter_readings.xml");

  xmlDoc.onload=getmessage;

  }

else

  {

  alert('Your browser cannot handle this script');

  }

}function getmessage()

{

//document.getElementById("to").innerHTML=

//xmlDoc.getElementsByTagName("to")[0].childNodes[0].nodeValue;

document.getElementById("save").innerHTML=

xmlDoc.getElementsByTagName("save")[0].childNodes[0].nodeValue;

// example line retined above. other variable lines removed,

// my equivalent below 

var save1 = xmlDoc.getElementsByTagName("save")[0].childNodes[0].nodeValue;

}

</script>

</head><body onload="loadXML()">

<h1>W3Schools Internal Note</h1>

<p><b>To:</b> <span id="to"></span><br />

// other variable lines removed

// my equivant below

<script type="text/javascript">

document.write("Save1  :"  + save1 + "<br>");

</script>

</p>

</body>

</html>

Sep 16 '07 #5

acoder

16,027

Expert Mod 8TB

You're accessing save1 before it is defined (it's defined after page load).

Don't use document.write - you can't use it after page load. You could use innerHTML of a div or span to display. Put this inside getmessage().

Sep 16 '07 #6

Gretsch

Thanks acoder for your guidance,

Perhaps you/someone would help me with the overall concept of where to put each bit of code, because I seem to be going round & round in circles trying things.

What my code needs to do is:
a) open an XML file and read some variables in.
b) perform some simple maths on the variables
c) Display the basic page .. so visitors can start reading something
d) Display the results of b) above top-left of the window (without any movement of existing text).

Please feel free to comment/overrule below:

I assume:
a) should be in the head - called 'onload'
b) should be in the head - called from above
c) is in body
d) is in body - and will need InnerHTML and 's

Sep 17 '07 #7

acoder

16,027

Expert Mod 8TB

What my code needs to do is:
a) open an XML file and read some variables in.
b) perform some simple maths on the variables
c) Display the basic page .. so visitors can start reading something
d) Display the results of b) above top-left of the window (without any movement of existing text).

Please feel free to comment/overrule below:

I assume:
a) should be in the head - called 'onload'
b) should be in the head - called from above
c) is in body
d) is in body - and will need InnerHTML and 's

a) ok
b) ok
c) ok
d) call from a), but after b).

The basic idea is that you can't access something until it is available. Once the XML file is completely loaded, the data becomes available. So the calculations must be made afterwards and likewise for the results. If you haven't made the calculations, you can't display the result, so this must come after b).

Sep 18 '07 #8

Gretsch

Hi,
I've taken all your advice above (I think/hope ;-) and got it all working for both IE and Firefox. - thanks
I then inserted an extra bit of code to update the figues every second, but now I get the error that my variable is "not defined".

I've added (for testing) 2 alerts to test where I'm losing the variable
The alert "TEST 1" (below) displays the variable OK,
but only a couple of lines later the alert "TEST 2" fails because the variable is not defined.

I'm tearing my hair out trying to see where the error is, can someone save my sanity (& hair) for me ;-) Thanks

[HTML]<html>
<head>
<script type="text/javascript">
var xmlDoc;
function loadXML()
{
// code for IE
if (window.ActiveXObject)
{
xmlDoc=new ActiveXObject("Microsoft.XMLDOM");
xmlDoc.async=false;
xmlDoc.load("meter_readings.xml");
getmessage();
}
// code for Mozilla, Firefox, Opera, etc.
else if (document.implementation && document.implementation.createDocument)
{
xmlDoc=document.implementation.createDocument(""," ",null);
xmlDoc.load("meter_readings.xml");
xmlDoc.onload=getmessage;
}
else
{
alert('Your browser cannot handle this script');
}

alert(dated); // Just for testing TEST 2

update_meter();

}
function getmessage()
{
var save = xmlDoc.getElementsByTagName("save")[0].childNodes[0].nodeValue;
var kwh = xmlDoc.getElementsByTagName("kwh")[0].childNodes[0].nodeValue;
var co2 = xmlDoc.getElementsByTagName("co2")[0].childNodes[0].nodeValue;
var daily_save = xmlDoc.getElementsByTagName("daily_save")[0].childNodes[0].nodeValue;
var daily_kwh = xmlDoc.getElementsByTagName("daily_kwh")[0].childNodes[0].nodeValue;
var daily_co2 = xmlDoc.getElementsByTagName("daily_co2")[0].childNodes[0].nodeValue;
var dated = xmlDoc.getElementsByTagName("dated")[0].childNodes[0].nodeValue;

alert(dated); // Just for testing TEST 1
}

// Functions to reformat the digits
// decimal digits truncation
Number.prototype.truncate = function(n) { return Math.round(this * Math.pow(10, n)) / Math.pow(10, n); }

// String reverse
String.prototype.reverse = function() { return this.split('').reverse().join(''); }

// integer thousand separators
Number.prototype.group = function()
{
var s = parseInt(this).toString().reverse(), r = '';
for (var i = 0; i < s.length; i++)
r += (i > 0 && i % 3 == 0 ? ',' : '') + s.charAt(i);
return r.reverse();
}

// format a number with n decimal digits and thousands separator
Number.prototype.format3s = function(n)
{
// truncate and the fractional part
var f = this.truncate(n);
// grouped integer part + dot + fractional part
return this.group();
}

// Timer to update the meter digits every x secs
function timerfunction()
{
start++;
document.getElementById("span_testing") .innerHTML = start; // for testing
alert(start)
alert(dated)
var current_date = new Date();
// Calc days elapsed between 'dated' & 'current_date
// The number of milliseconds in one day
var ONE_DAY = 1000 * 60 * 60 * 24
// Convert both dates to milliseconds
var date1_ms = current_date.getTime()
var date2_ms = Date.parse(dated);
// Calculate the difference in milliseconds
var difference_ms = Math.abs(date1_ms - date2_ms)
// Convert back to days
var days_elapsed = (difference_ms/ONE_DAY)

var current_kwh = ((daily_kwh * days_elapsed) + (kwh * 1));
document.getElementById("span_kwh") .innerHTML = current_kwh.format3s(0);

var current_co2 = ((daily_co2 * days_elapsed) + (co2 * 1));
document.getElementById("span_co2") .innerHTML = current_co2.format3s(0);

var current_save = ((daily_save * days_elapsed) + (save * 1));
document.getElementById("span_save") .innerHTML = current_save.format3s(0);
}

function update_meter()
{
start = 0; //start number
window.setInterval("timerfunction()", 1000); // 1000 = 1 second
}

</script>
</head>
<body onload="loadXML()">

<table border="0" width="208" cellspacing="0" cellpadding="0" background="images/meter_back.gif">
<tr>
<td align="right" height="25" width="65">
<td align="right" height="25" width="130">
<td align="right" height="25">
<tr>
<td align="right" width="65" height="25">
kWh:</td>
<td align="right" width="130" height="25">

?,???,???

<td align="right" height="25">
<tr>
<td align="right" width="65" height="25">
CO2 kg:</td>
<td align="right" width="130" height="25">

?,???,???

<td align="right" height="25">
<tr>
<td align="right" width="65" height="25">
£:</td>
<td valign="bottom" align="right" width="130" height="25">

?,???,???

<td valign="top" align="right" height="25">
<tr>
<td align="right" height="25" width="65"></td>
<td valign="top" align="right" height="25" width="130">
<td valign="top" align="right" height="25">
</tr>
</table>


For testing: xxxxx

</body>

</html>[/HTML]

Sep 27 '07 #9

acoder

16,027

Expert Mod 8TB

Where do you get the variable not defined error?

The TEST 2 alert will not work because dated is defined in getmessage().

Sep 27 '07 #10

Gretsch

Where do you get the variable not defined error?().

When I run the program in both IE & Firefox (ie before I put in the test alerts.

The TEST 2 alert will not work because dated is defined in getmessage().

..but getmessage runs before TEST 2.
ie I inserted the TEST 1 alert in getmessage (to confirm it was running & retreiving the variables, which it is)
.. then inserted TEST 2 alert ... by which time it is lost.

Once defined, a variable's scope is global isn't it?

Sep 27 '07 #11

acoder

16,027

Expert Mod 8TB

Once defined, a variable's scope is global isn't it?

No it's not. See this article.

Sep 28 '07 #12

Gretsch

No it's not. See this article.

That explains a lot of the issues I've been having.
An excellent forum.
Thanks VERY much for your time & help :-)

Sep 28 '07 #13

acoder

16,027

Expert Mod 8TB

Glad I could be of help and thank pbmods for that article.

Post again if you have any more questions.

Sep 28 '07 #14

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