javascript - Uncaught (in promise) TypeError: Cannot read property 'filter' of undefined in Javascript

Question

import React, { Component } from 'react';
import DegreeToggle from './DegreeToggle';
import DayCard from './DayCard';
class WeekContainer extends Component {
state = {
fullData: [],
dailyData: [],
degreeType: "fahrenheit"
}
componentDidMount = () => {
const weatherURL =
`http://api.openweathermap.org/data/2.5/weather?q=London,uk&APPID=c1bab0c96843878b6348982015110ecc`

fetch(weatherURL)
.then(res => res.json())
.then(data => {
  const dailyData = data.list.filter(reading => reading.dt_txt.includes("18:00:00"))
  this.setState({
    fullData: data.list,
    dailyData: dailyData
  }, () => console.log(this.state))
})
}
formatDayCards = () => {
return this.state.dailyData.map((reading, index) => <DayCard reading={reading} key={index} />)
}
updateForecastDegree = event => {
this.setState({
  degreeType: event.target.value
}, () => console.log(this.state))

} render() { return ( 5-Day Forecast. New York, US {this.formatDayCards()} ) } } export default WeekContainer;

我正在开发一个反应 js 应用程序，我收到错误 Uncaught (in promise) TypeError: Cannot read property 'filter' of undefined

标签： javascriptreactjs