[Vue warn]: Property or method "content" 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. See: https://v2.vuejs.org/v2/guide/reactivity.html#Declaring-Reactive-Properties.
属性或方法“content”不是在实例上定义的，而是在渲染期间引用的。通过初始化属性，确保该属性是可响应的，无论是在data选项中，还是对于基于类的组件。见:https://v2.vuejs.org/v2/guide/reactivity.html Declaring-Reactive-Properties。