Javascript对网页输入框的字数限制
js对输入框的字数限制，限制文本框输入的字符数,若达到数目则停止其输入!代码如下：
01.< !DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
02.<html xmlns="http://www.w3.org/1999/xhtml">
03.<head>
04.<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
05.<title>无标题文档</title>
06.<script type="text/javascript">
07.
var textCounter=function (field,counter,maxlimit){
08.
var charcnt = field.value.length;
09.
if (charcnt > maxlimit) {
10.
field.value = field.value.substring(0, maxlimit);
11.
}else {
12.
document.getElementById(counter).innerHTML=charcnt;
13.
}
14.
}
15.</script>
16.</head>
17.<body>
18.<p><span id="progressbar1">0</span>/12</p>
19.<form><input type="text" id="maxcharfield" size="34"/>
20.</form>
21.<script type="text/javascript">
22.
document.getElementById("maxcharfield").onfocus = document.getElementById("maxcharfield").onkeydown = document.getElementById("maxcharfield").onkeyup = function(){
23.
textCounter(this,'progressbar1',12);
24.
}
25.</script>
26.</body>
27.</html>