傳播不空

Question

ES6傳播工作不會以這種方式工作

I have this.state = { sortedKey: null } in my constructor and I do 

this.setState({ 
sortedKey: [...this.state.sortedKey, 'something'] 
}) 

我的Cannot convert undefined or null to object錯誤？

Answer 1

var state = { "sortedKey": [] }; 
 

 
var newState = {"sortedKey": [...state.sortedKey, 'something']}; 
 

 
console.log(newState)