js字符串判断 

<!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>计算字符-Demo1</title>
</head>
<body>
<div id="tips">最多10个字</div>
<input type="text" value="" onkeyup="test(this)" />
<script type="text/javascript">
var num=15;
     function len(x){
     var text=x;
    return text.replace(/[^\x00-\xff]/g,"**").length;        //汉字替换为2字符
    }
function test(obj){
var tips = document.getElementById("tips");
var str = obj.value;
var n=Math.ceil(len(str)/2);
    if((num-n)>0){
    tips.innerHTML="你还可以输入"+(num-n)+"个字";
    }else{
    thips.innerHTML="你还可以输入"+(n-num)+"个字";
    }
    
}
</script>
</body>
</html>

写法2：

<!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>计算字符-Demo1</title>
</head>
<body>
<div id="tips">最多10个字</div>
<input type="text" value="" onkeyup="test(this)" />
<script type="text/javascript">
var num=15;
     String.prototype.len=function(){
    return this.replace(/[^\x00-\xff]/g,"**").length;        //汉字替换为2字符
    }
function test(obj){
var tips = document.getElementById("tips");
var str = obj.value;
var n=Math.ceil(str.len()/2);
    if((num-n)>0){
    tips.innerHTML="你还可以输入"+(num-n)+"个字";
    }else{
    thips.innerHTML="你还可以输入"+(n-num)+"个字";
    }
    
}
</script>
</body>
</html>

 

posted @ 2013-10-19 12:06  tinyphp  Views(336)  Comments(0)  Edit  收藏  举报