vue.runtime.esm.js?2b0e:619 [Vue warn]: Property or method "beforeUpload" 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://vuejs.org/v2/guide/reactivity.html#Declaring-Reactive-Properties.
单词拼写错了吧： beforeUpdate
Property or method "XXX" is not defined，一般都是没定义的意思