js代码小记（判断textbox的长度并且固定最多收入字符）

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!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" /
titleUntitled 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 (intlentestleng)
                {
                    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
BGroup description/BBRTEXTAREA id=desc onkeydown=GC_UpdateCharCount() onkeyup=GC_UpdateCharCount()  onblur="isOver(this);"style="WIDTH: 99%" name=desc rows=4 cols=50/TEXTAREA
            BRLetters remaining: SPAN id=remainingchars
            SCRIPT language=javascript1.2!--
              GC_UpdateCharCount();
              //--/SCRIPT/SPANNOSCRIPT300 characters allowed /NOSCRIPT
/body
/html