微博输入数字
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>为什么“表情”“图片”前面插入的图片使用的是“background-image”，而不是用img</title>
<style>
body{font-size:12px;}
.box{
width:600px;
height:160px;
border:10px solid pink;
margin:20px auto;
padding:10px;
}
.box1{
float:right;
margin-right:4px;
font-size:14px;
color: #888;
}
#number{
font-size:16px;
font-weight:bold;
}
#text{
width:600px;
height:100px;
display:block;
}
#sp1,#sp2,#sp3,#sp4,#sp5,#sp6{
width:30px;
height:32px;
line-height:32px;
padding-left:22px;
margin-right:8px;
}
#sp1{background:url(static/images/an5.png) no-repeat left 45%;background-size:46%;}
#sp2{background:url(static/images/an4.png) no-repeat left 45%;background-size:46%;}
#sp3{background:url(static/images/an3.png) no-repeat left 45%;background-size:46%;}
#sp4{background:url(static/images/an2.png) no-repeat left 45%;background-size:46%;}
#sp5{background:url(static/images/an1.png) no-repeat left 45%;background-size:46%;}
#sp6{margin-left:160px;color:#888;}
#bt{width:80px;height:30px;border:none;outline:none;color:#fff;background:orange;position:relative;right:-9px;top:2px;}
</style>
</head>
<body>
<div class="box">
<img src="static/images/12.png">
<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">长微博</span>
<span id="sp6">公开</span>
<input type="button" value="发布" id="bt">
</div>
<script>
function getObj(idName){
return document.getElementById(idName);
}
var text,number,bt,m,len;
text = getObj('text');
number = getObj('number');
bt = getObj('bt');
text.onkeydown = function(){
if(text.value.length == undefined){
len = 0;
}else{
len = text.value.length;
}
m = 140 - len;
number.innerHTML = m;
if(m<0){
number.style.color = 'red';
}else{
number.style.color = '#888';
}
}
bt.onclick = function(){
if(text.value.length == undefined){
len = 0;
}else{
len = text.value.length;
}
m = 140 - len;
number.innerHTML = m;
if(m == 140){
alert("输入框不能为空");
text.focus();
}else if(m < 0){
alert("输入的字符不能超过140个");
text.focus();
}else{
alert("发表成功");
}
}
</script>
</body>
</html>