類型反應打字稿上不存在屬性

Question

我是打字稿的新手，誰能告訴我為什么會出現這個錯誤？

“應用程序”類型上不存在屬性“間隔”。

interface State {
  userInput:string[];
  secondsPassed:number;
  }


class App extends React.Component<any, State>{
    state:State = {
      userInput:[],
      secondsPassed:0
    }
  startTimer = () => {
      this.interval = setInterval( () => {
        this.setState(() =>{
          return {secondsPassed: this.state.secondsPassed+1}
        })
      },1000)
    
  }

Answer 1

嘗試這樣的事情：

 const interval = setInterval(() => {
    this.setState(() =>{
          return {secondsPassed: this.state.secondsPassed+1}
        })
      },1000)

Answer 2

Typescript 是一種靜態類型語言。 這部分意味着您必須在賦值之前聲明類的變量。 簡單地聲明interval如下：

class App extends React.Component<any, State>{
  interval

  state:State = {
    userInput:[],
    secondsPassed:0
  }
  startTimer = () => {
    this.interval = setInterval( () => {
      this.setState(() =>{
        return {secondsPassed: this.state.secondsPassed+1}
      })
    },1000)

  }

Answer 3

第一個答案很接近，解決方案如下所示：

 class App extends React.Component<any, State>{
      private interval: any ;
        state:State = {
          userInput:[],
          secondsPassed:0
        }
      startTimer = () => {
          this.interval = setInterval( () => {
            this.setState(() =>{
              return {secondsPassed: this.state.secondsPassed+1}
            })
          },1000)
        
      }