Solved

Script is null or not an object

Posted on 2004-10-09
5
173 Views
Last Modified: 2011-10-03
Hi, experts.
I try the following script but browser shows -- document.getElementsByTagName("body")[0].style.fontSize = font_size + "px"; is null or not an object -- How can I fix it ?



 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
<html lang="en">
<head>
<title>Q_21154225</title>
<script type="text/javascript">
myPix = new Array("dots/digital1.gif","dots/digital2.gif","dots/digital3.gif","dots/digital4.gif","dots/digital5.gif","dots/digital6.gif","dots/digital7.gif")
thisPic = 3
imgCt = myPix.length -1
var font_size = 14;
var MAX = 17;
var MIN = 11;
function processPrevious(num)
{if (document.images && thisPic > 0) {
thisPic--
document.myPicture.src=myPix[thisPic]
}
}
function processNext(num)
{
if (document.images && thisPic < imgCt) {
thisPic++
document.myPicture.src=myPix[thisPic]
}
}
function adjust_text(num)
{
font_size += num;
if(font_size > MAX)
{
font_size = MAX;
}
if(font_size < MIN)
{
font_size = MIN;
}
document.getElementsByTagName("body")[0].style.fontSize = font_size + "px"; <--- Error
document.getElementById("test").style.fontSize = (font_size - 3) + "px";
}
adjust_text(0);
</script>
</head>
<body onload="adjust_text(0);">
<table width="329" border="0">
<tr>
<td width="117" align="right"><div class="style2">Change font size</div></td>
<td width="48" align="right"><A HREF="javascript:processPrevious(adjust_text(-1))"><IMG SRC="arrows/reverse.gif" width="40" height="20" BORDER=0></a></td>
<td width="98" align="center"><IMG SRC="dots/digital4.gif" NAME="myPicture" width="81" height="20"></td>
<td width="48" align="left"><A HREF="javascript:processNext(adjust_text(1))"><IMG SRC="arrows/forward.gif" width="40" height="20" BORDER=0></a></td>
</tr>
</table>
<p>This is the body text</p>
<p id="test">This is the second body text</p>
<a href="font_change2.html"> 2nd page </a>
</body>
</html>
0
Comment
Question by:mingchih
  • 3
  • 2
5 Comments
 
LVL 15

Expert Comment

by:Colosseo
ID: 12267678
Hi

right at the end of your script section you call

adjust_text(0);

This is trying to run before the page loads hence before body exists

If you remove this line it will be called by the onload you already have on your body tag

HTH

Scott
0
 

Author Comment

by:mingchih
ID: 12267736
yes, i did....

document.getElementsByTagName("body")[0].style.fontSize = font_size + "px"; <--- Error
document.getElementById("test").style.fontSize = (font_size - 3) + "px";
}
adjust_text(0); <-- is this right ?
0
 
LVL 15

Accepted Solution

by:
Colosseo earned 500 total points
ID: 12268349
Hi

no with that there the code will run before body exists...

you need to remove the adjust_text(0); .... so..

document.getElementsByTagName("body")[0].style.fontSize = font_size + "px";
document.getElementById("test").style.fontSize = (font_size - 3) + "px";
}

because it will be called here...

<body onload="adjust_text(0);">

try this

 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
<html lang="en">
<head>
<title>Q_21154225</title>
<script type="text/javascript">
myPix = new Array("dots/digital1.gif","dots/digital2.gif","dots/digital3.gif","dots/digital4.gif","dots/digital5.gif","dots/digital6.gif","dots/digital7.gif")
thisPic = 3
imgCt = myPix.length -1
var font_size = 14;
var MAX = 17;
var MIN = 11;
function processPrevious(num)
{if (document.images && thisPic > 0) {
thisPic--
document.myPicture.src=myPix[thisPic]
}
}
function processNext(num)
{
if (document.images && thisPic < imgCt) {
thisPic++
document.myPicture.src=myPix[thisPic]
}
}
function adjust_text(num)
{
font_size += num;
if(font_size > MAX)
{
font_size = MAX;
}
if(font_size < MIN)
{
font_size = MIN;
}
document.getElementsByTagName("body")[0].style.fontSize = font_size + "px";
document.getElementById("test").style.fontSize = (font_size - 3) + "px";
}
</script>
</head>
<body onload="adjust_text(0);">
<table width="329" border="0">
<tr>
<td width="117" align="right"><div class="style2">Change font size</div></td>
<td width="48" align="right"><A HREF="javascript:processPrevious(adjust_text(-1))"><IMG SRC="arrows/reverse.gif" width="40" height="20" BORDER=0></a></td>
<td width="98" align="center"><IMG SRC="dots/digital4.gif" NAME="myPicture" width="81" height="20"></td>
<td width="48" align="left"><A HREF="javascript:processNext(adjust_text(1))"><IMG SRC="arrows/forward.gif" width="40" height="20" BORDER=0></a></td>
</tr>
</table>
<p>This is the body text</p>
<p id="test">This is the second body text</p>
<a href="font_change2.html"> 2nd page </a>
</body>
</html>

Scott
0
 

Author Comment

by:mingchih
ID: 12268846
thanks so much !!
0
 
LVL 15

Expert Comment

by:Colosseo
ID: 12269240
Your welcome and thanks for the grade

Cheers

Scott
0

Featured Post

Free Tool: Site Down Detector

Helpful to verify reports of your own downtime, or to double check a downed website you are trying to access.

One of a set of tools we are providing to everyone as a way of saying thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

This article shows how to create and access 2-dimensional arrays in JavaScript.  It includes a tutorial in case you are just trying to "get your head wrapped around" the concept and we'll also look at some useful tips for more advanced programmers. …
The task A number given should be formatted for easy reading by separating digits into triads. Format must be made inline via JavaScript, i.e., frameworks / functions are not welcome. So let’s take a number like this “12345678.91¿ and format i…
The viewer will learn the basics of jQuery, including how to invoke it on a web page. Reference your jQuery libraries: (CODE) Include your new external js/jQuery file: (CODE) Write your first lines of code to setup your site for jQuery.: (CODE)
The viewer will learn the basics of jQuery including how to code hide show and toggles. Reference your jQuery libraries: (CODE) Include your new external js/jQuery file: (CODE) Write your first lines of code to setup your site for jQuery…

860 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question