Solved

Script is null or not an object

Posted on 2004-10-09
5
165 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
Comment Utility
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
Comment Utility
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
Comment Utility
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
Comment Utility
thanks so much !!
0
 
LVL 15

Expert Comment

by:Colosseo
Comment Utility
Your welcome and thanks for the grade

Cheers

Scott
0

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