微博留言字数输入限制
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>微博留言</title>
<style>
*{margin:0;padding:0;}
.box{width: 600px;height: 200px;margin:0 auto;border:5px solid pink;border-radius: 5px;padding: 10px}
.top img{float: left;}
.top p{display: block;width: 50%;float: right;text-align: right;font-size: 12px;line-height: 24px;color:#888}
.top span{font-size: 16px;font-weight: bold;}
#text{width: 100%;height: 145px;border-radius: 5px;margin-top:5px;border-color:#ccc;}
#sp1,#sp2,#sp3,#sp4,#sp5,#sp6{float: left;width: 50px;text-align: right;height: 24px;line-height: 24px;font-size: 12px;margin-left: 5px}
#sp1{background: url(images/an5.png) no-repeat left center;}
#sp2{background: url(images/an4.png) no-repeat left center;}
#sp3{background: url(images/an3.png) no-repeat left center;}
#sp4{background: url(images/an2.png) no-repeat left center;}
#sp5{background: url(images/an1.png) no-repeat left center;width: 60px;}
#sp6{margin-right: 15px}
.button{float: right;}
#button{border: none;height: 24px;background: #ffc09f;color:white;width: 60px;border-radius: 3px}
</style>
<script>
var text,number,m
window.onload=function(){
text=document.getElementById('text')
number=document.getElementById('number')
button=document.getElementById('button')
text.onkeyup=function aa(){
m=140-text.value.length
if(m<0){
number.style.color="red"
}else{
number.style.color="#888"
}
number.innerHTML=m
}
button.onclick=function(){
if(m==140){
alert("你还没有输入!");
text.focus()
}else if(m>130){
alert("字数少于10，不可发布!")
text.focus()
}else if(m<0){
alert("字数太多，不可发布!")
text.focus()
}else{
alert("发布成功！")
}
}
aa()
}
</script>
</head>
<body>
<div>
<div>
<img src="images/12.png" alt="">
<p>还可输入<span id="number"></span>字</p>
</div>
<textarea id="text"></textarea>
<span id="sp1">表情</span>
<span id="sp2">图片</span>
<span id="sp3">视屏</span>
<span id="sp4">话题</span>
<span id="sp5">长微博</span>
<div>
<span id="sp6">公开</span>
<input type="button" value="发布" id="button">
</div>
</div>
</body>
</html>