Property or method "res" is not

Property or method "res" is not defined on the instance but referenced during render. Make sure that this property is reactive, either in the data option, or for class-based components, by initializing the property

百度的译文如下

属性或方法“res”未在实例上定义，但在呈现期间被引用。通过初始化该属性，确保该属性是被动的，无论是在数据选项中，还是对于基于类的组件

Vue中报这样的错误,让我找找了足足大半天,快要吐血了....其实就是使用某一个属性但是没有在,data中定义,故报错!

所以,必须在下面定义才好用!!!
<input :select='res'>

data(){
    return {
        res:null
    }
}