<!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=utf-8" />
<title></title>
</head>
<body>
<input type="text" onkeyup="checkLength(this);"/><span id="words" style="color:Red;">200</span>
<input type="text" onkeyup="checkLength(this);"/><span id="wordss" style="color:Red;">200</span>
<input type="text" onkeyup="checkLen(this);"/><span id="word" style="color:Red;">50</span>
<script type="text/javascript">
function checkLength(words) {
var maxChars = 200; //
if(words.value.length > maxChars){
alert("您出入的字数超多限制!");
// 超过限制的字数了就将 文本框中的内容按规定的字数 截取
words.value = words.value.substring(0,maxChars);
return false;
}else{
var curr = maxChars - words.value.length;
document.getElementById("words").innerHTML = curr.toString();
document.getElementById("wordss").innerHTML = curr.toString();
return true;
}
}
function checkLen(words) {
var minChars = 50; //
if(words.value.length > minChars){
alert("您出入的字数超多限制!");
// 超过限制的字数了就将 文本框中的内容按规定的字数 截取
words.value = words.value.substring(0,minChars);
return false;
}else{
var curr = minChars - words.value.length;
document.getElementById("word").innerHTML = curr.toString();
return true;
}
}
</script>
</body>
</html>
原文：http://www.cnblogs.com/hellman/p/4078604.html