<div id="app">
	<test content="123"></test>
</div>

Vue.component("test",{
	template: '<div>{{content}}</div>',
    props:{
      content: {
        type: String,
        required: false,
        default: "tom",
        validator: function(value) {
          return (value.length > 5);
        }
      }
    }
});