摘要：<!DOCTYPE html> <html> <head> <meta charset="UTF-8">
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>微博</title>
<style>
body {
font-size: 12px;
}
.box {
width: 600px;
height: 160px;
border: 8px solid pink;
margin: 0 auto;
padding: 10px;
}
img {
float: left;
}
.box-num {
float: left;
margin-left: 255px;
width: 150px;
height: 24px;
font-size: 14px;
text-align: right;
color: #888;
}
.box-num span {
font-size: 16px;
font-weight: bold;
}
#text {
width: 594px;
height:100px;
border: 1px solid #ccc;
margin-top: 5px;
clear: both;
}
.box .item1, .item2, .item3, .item4, .item5, .item6 {
float: left;
width: 30px;
height: 36px;
line-height: 32px;
padding-left: 26px;
}
.item1 {
background: url(images/an5.png) no-repeat left center;
}
.item2 {
background: url(images/an4.png) no-repeat left center;
}
.item3 {
background: url(images/an3.png) no-repeat left center;
}
.item4 {
background: url(images/an2.png) no-repeat left center;
}
.item5 {
background: url(images/an1.png) no-repeat left center;
width: 40px;
}
.item6 {
margin-left: 160px;
margin-right: 14px;
color: #888;
}
#but {
float: left;
border: none;
background: #ff6500;
color: #fff;
width: 80px;
height: 30px;
border-radius: 5px;
}
</style>
<script>
var text, number, m, but;
window.onload = function() {
text = document.getElementById('text');
number = document.getElementById('number');
but = document.getElementById('but');
text.focus();
text.onkeyup = function aa() {
m = 140 - text.value.length;
if (m < 0) {
number.style.color = 'red';
} else {
number.style.color = '#888';
}
number.innerHTML = m;
}
but.onclick = function() {
if (text.value == "") {
alert('你没有输入内容');
text.focus();
} else if (m < 0) {
alert('你输入的内容超过了140个字');
text.focus();
} else {
alert('发布成功')
}
}
a();
}
</script>
</head>
<body>
<div class="box">
<img src="images/12.png">
<div class="box-num">还可以输入<span id="number">140</span>字</div>
<textarea id="text"></textarea> <span class="item1">表情</span>
<span class="item2">图片</span>
<span class="item3">视频</span>
<span class="item4">话题</span>
<span class="item5">长微博</span>
<span class="item6">公开</span>
<input type="button" value="发布" id="but">
</div>
</body>
</html>如果按钮提交if语句使用 m==8，默认进入不进行操作点击提交按钮，会提示发布成功，使用text.value == ""，就不会出现这个问题。
批改老师：韦小宝批改时间：2019-02-02 13:40:49
老师总结：写的很不错 通过这种案例可以练习我们的前端基础 没事要多练习练习哦！
