Javascript对网页输入框的字数限制

http://www.itjxue.com  2015-08-06 23:11  来源:未知  点击次数: 

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>

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