js微博发布字数判断
<!DOCTYPE html>
<html lang="en">
<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>Document</title>
</head>
<body>
<h4>还能输入<span id="number">140</span>个字</h4>
<textarea name="" id="text1" ></textarea>
<br>
<input type="button" id="submit" value="发布">
<script>
var a
document.getElementById('text1').onkeyup=function(){
a = 140 - document.getElementById('text1').value.length;
document.getElementById('number').innerText=a;
if(a<0){
document.getElementById('number').style.color='red';
}else{
document.getElementById('number').style.color='';
}
}
document.getElementById('submit').onclick = function(){
if(a<0){
alert('字数过多 发布失败');
}else{
alert('发布成功');
}
}
</script>
</body>
</html>利用js键盘按下松开事件实时更新字数