JS Code note (judge the length of textbox and fix the maximum number of characters)

<! Doctype HTML public "-// W3C // dtd xhtml 1.0 transitional // en" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd" >
< Html Xmlns = "Http://www.w3.org/1999/xhtml" >
< Head >
< Meta HTTP-equiv = "Content-Type" Content = "Text/html; charset = gb2312"   />
< Title > Untitled document </ Title >
< Script Language = Javascript1.3 > <! --
VaR Testleng = 300 ; // How many strings are allowed

Function Gc_updatecharcount () {
VaR Desc_el = Document. getelementbyid ('desc ');
VaR Remainingchars_el = Document. getelementbyid ('remainingchars ');

VaR Num_remaining = Testleng - Desc_el.value.length;

If (Num_remaining > =   0 ) {
Remainingchars_el.innerhtml=Num_remaining;
}   Else   {
Remainingchars_el.innerhtml =   " <Font color = Red> "   +
( - Num_remaining + '') +   " Characters over </font> " ;
}
}
Function Isover (stext)
{
VaR Intlen = Stext. value. length;
If (Intlen > Testleng)
{
alert ( " the number of words used to describe a feature must be less than or equal to " + testleng);
stext. focus ();
stext. select ();
}
}

// --> </SCRIPT>
</ Head >

< Body >
< B > Group description </ B > < BR > < Textarea ID = Desc onkeydown = Gc_updatecharcount () onkeyup = Gc_updatecharcount () onblur = " Isover (this ); " Style = " Width: 99% " Name = Desc rows = 4 Cols = 50 > </ Textarea >  
< BR > Letters remaining: < SPAN ID = Remainingchars >
< Script Language = Javascript1. 2 > <! --
Gc_updatecharcount ();
// --> </SCRIPT> </span> <NoScript> 300 characters allowed </NoScript>
</ Body >
</ Html >

Result reference: www.lostfound.cn/coutchar.html