react function state is not defined no-undef

I create this function startStop for such button to start and pause a timer. The error is "Line 108:22: 'sessionLength' is not defined no-undef". I think it might have to do with binding? but what's wrong?

import React, { Component } from 'react';  import './App.css';    class App extends Component {    state = {      breakLength: 5,      sessionLength: 25,      timerState: "paused",    }      constructor(props) {      super(props)      this.startStop = this.startStop.bind(this)    }    startStop() {         if (this.state.timerState === "paused") {        this.setState({          timerState: setInterval(() => decrement(), 1000)        }, function () {console.log(this.state.timerState)})        }            else if (this.state.timerState !== "paused") {        console.log(this.state.timerState)        clearInterval(this.state.timerState)        this.setState({          timerState: "paused"        }, function () {console.log(this.state.timerState)})      }        this.setState({        sessionLength: sessionLength - remaining      }, function () {console.log(this.state.sessionLength)})      }    

https://stackoverflow.com/questions/65623319/react-function-state-is-not-defined-no-undef January 08, 2021 at 12:06PM