<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
<script src="https://cdn.jsdelivr.net/npm/vue/dist/vue.js"></script>
<style>
.red{
color:red
}
.font{
font-size: 30px;
}
</style>
</head>
<body>
<div id="app">
<span :class="classObject">hello world</span>
</div>
<script>
var v= new Vue({
el:"#app",
data:{
isTrue:true
},
computed:{
classObject:function(){
return ['font',{'red':this.isTrue}]
}
}
});
</script>
</body>
</html>