vue how to customize a filter

vue how to customize a filter?

html code:

<div id="app">
<input type="text" v-model="msg" />
{{msg| capitalize }}
</div>
JS代码：

var vm=new Vue({
el:"#app",
data:{
msg:''
},
filters: {
capitalize: function (value) {
if (!value) return ''
value = value.toString()
return value.charAt(0).toUpperCase() + value.slice(1)
}
}
})
全局定义过滤器

Vue.filter ( 'capitalize', function (value) {
IF (! Value) return ''
value = value.toString ()
return value.charAt (0) .toUpperCase () value.slice + (. 1)
})
filter value of the received expression (msg) as the first parameter. filter will receive capitalize msg value as the first parameter.