<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>javascript学习之textarea控制输入字数限制</title>
<style type="text/css">
body{font-size: 12px;}
.box{width: 600px; height: 160px; border:8px solid pink; margin: 0px auto;padding: 10px;}
.box1{float:right; margin-left: 255px; width: 150px; height: 25px; text-align: right;font-size: 14px; color: #888;}
.box1 span{font-size: 16px; font-weight: bold;}
#text{width: 600px;height: 100px;border: 1px solid #888;margin-top: 5px;}
.box #sp1,#sp2,#sp3,#sp4,#sp5,#sp6{float: left;width: 30px;height: 32px;line-height: 32px;padding-left: 26px;}
#sp5{width: 40px;}
#sp6{margin-left: 150px; margin-right: 15px; color: #888;}
#bt{float:left; width: 80px; height: 30px; border: none; background:#ffc09f; color: #fff; border-radius: 5px;}
</style>
<script type="text/javascript">
var text;
var number;
var m;
window.onload = function(){
text = document.getElementById('text');
number = document.getElementById('number');
bt = document.getElementById('bt');
text.onkeyup = function aa(){
m = 140 - text.value.length; //限制字数
if(m < 0){
number.style.color = 'red';
}else{
number.style.color = '#888';
}
number.innerHTML = m;
}
bt.onclick = function(){
if(m==140){
alert('您还没有输入内容！');
text.focus();
}else if(m < 0){
alert('您的内容超过限制字数！');
text.focus();
}else{
alert('发布成功！');
}
}
aa();
}
</script>
</head>
<body>
<div class="box">
<div class="box1">还可以输入<span id="number">140</span>字</div>
<textarea id="text"></textarea>
<span id="sp1">表情</span>
<span id="sp2">图片</span>
<span id="sp3">视频</span>
<span id="sp4">话题</span>
<span id="sp5">长微薄</span>
<span id="sp6">公开</span>
<input type="button" value="发布" id="bt" name="">
</div>
</body>
</html>
