三目运算符
<!DOCTYPE html>
<html lang='en'>
<head>
<meta charset='UTF-8'>
<meta http-equiv='X-UA-Compatible' content='IE=edge'>
<meta name='viewport' content='width=device-width, initial-scale=1.0'>
<script src='https://unpkg.com/vue/dist/vue.js'></script>
<title></title>
</head>
<body>
<div id='app'>
<div :style="{color:danger?'red':'black'}">提示消息</div>
</div>
<script>
new Vue({
el:'#app',
data:{
danger:false
}
}
)
</script>
</body>
</html>
