abstract：<!DOCTYPE html><html><head> <meta charset="utf-8"> <title>Document</title> <link rel="stylesheet" type="text/css" href=""
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Document</title>
<link rel="stylesheet" type="text/css" href="">
<link rel="shortcut icon" type="image/x-icon" href="">
<style type="text/css">
body{font-size: 12px;}
.box{width: 600px;height: 160px;border: 10px solid pink;margin: 0px auto;padding: 10px;}
img{float: left;}
.box1{float: left;margin-left: 225px;width: 150px;height: 24px;text-align: right;font-size: 14px;color: #888;}
.box1 span{font-size: 16px;font-weight: bold;}
#text{width: 600px;height: 100px;border: 1px solid #ccc;margin-top: 5px;}
.box #sp1,#sp2,#sp3,#sp4,#sp5,#sp6{float: left;width: 30px;height: 32px;line-height: 32px;padding-left: 26px;}
#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: 40px;}
#sp6{margin-left: 150px;margin-right: 15px;color: #888;}
#bt{float: left;width: 80px;height: 30px;border: none;background:#ffc09f;color: #fff;border: 5px;}
</style>
<script type="text/javascript">
var text,number,m,bt;
m = 140;
window.onload = function(){
text = document.getElementById("text");
number = document.getElementById("number");
bt = document.getElementById("bt");
text.onkeyup =function aa(){
m = m- text.value.length;
if(m<0){
number.style.color = "red";
}else{
number.style.color = "#888";
}
number.innerHTML = m;
}
bt.onclick =function bb(){
if(m==140){
alert("你还没有输入");
text.focus();
}else if(m<0){
alert("字数太多，不可以发布");
text.focus();
}else{
alert("发布成功");
}
}
}
</script>
<body>
<div class="box">
<img src="images/12.png">
<div class="box1">还可以输入<span id = "number"></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">长微博</span>
<span id = "sp6">公开</span>
<input type="button" name="发布" value="发布" id="bt">
</div>
</body>
</html>
总结：在视频的案例代码中，如果没有点击textarea，直接点击发布，可以发布成功，我检查了一下是因为m没有给初始值，那时候m为0。我修改了一下，给了初始值。
Correcting teacher：灭绝师太Correction time：2019-02-21 15:36:05
Teacher's summary：bb()这个函数名可以去掉,要理解代码含义,不可照葫芦画瓢哦!