<!doctype html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title> </title>
</head>
<body>
<span id="span"></span>
<textarea name="#" id="show" cols="30" rows="10"></textarea>
<script type="text/javascript">
var oSpan=document.getElementById('span');
var oShow=document.getElementById('show');
var timer=null;
// oShow.oninput=function(){ // firfox 和chrome 兼容 ie8不兼容
// oSpan.innerHTML=this.value.length;
// }
// oShow.onpropertychange=function(){ // //此事件只有ie兼容 ie10 以下
// oSpan.innerHTML=this.value.length
// }
//以下这种写法 ie 火狐 chrome都兼容
oShow.onfocus=function(){
clearInterval(timer);
timer=setInterval(function(){
oSpan.innerHTML=oShow.value.length;
},5000)
}
oShow.onblur=function(){
clearInterval
}
</script>
</body>
</html>