js代码小记（判断textbox的长度，并且固定最多收入字符）
<!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;//允许多少字符串填入
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("描述特征的内容的字数必修小于或者等于 "+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>
