实例如下：
<!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>无标题文档</title>
<script language="javascript">
function checkLength(which) {
var oTextCount = document.getElementById("char");
iCount = which.value.replace(/[^/u0000-/u00ff]/g,"aa");
oTextCount.innerHTML = "<font color=#FF0000>"+ iCount.length+"</font>";
which.style.border = '1px dotted #FF0000';
which.size=iCount.length+2;
}
</script>
</head>
<body>
<input name="words" size="2" onkeyup="checkLength(this)"/>
<span id="char">0</span>个字符
</body>
</html>
以上这篇Input文本框随着输入内容多少自动延伸的实现就是小编分享给大家的全部内容了，希望能给大家一个参考，也希望大家多多支持。