NodeJS:无法读取未定义的属性'length'
[当我在nodejs中运行node app.js时,错误消息显示'无法读取未定义的属性'length'。我已经安装了所有相关的库(例如,请求),并查看了不同的相关帖子。但是,问题仍然存在。
[请您告知我如何解决。非常感谢!
Windows 10家用PCVisual Studio代码
//app.js
const geocode = require('./utils/geocode')
const forecast = require('./utils/forecast')
geocode('Boston', (error, data) => {
console.log('Error', error)
console.log('Data', data)
forecast(data.latitude, data.longitude, (error, data) => {
console.log('Error', error)
console.log('Data', data)
})
})
// forecast.js
const request = require('request')
const forecast = (latitude, longitude, callback) => {
const url =
'/' +
latitude + ',' + longitude
request({ url: url, json: true }, (error, response) => {
if (error) {
callback('Unable to connect to weather service!', undefined)
} else if (response.body.error) {
callback('Unable to find location', undefined)
} else {
callback(undefined, response.body.daily.data[0].summary + ' It is
currently ' + response.body.currently.temperature + ' degress out. There
is a ' + response.body.currently.precipProbability + '% chance of rain.')
}
})
}
module.exports = forecast
// geocode.js
const request = require('request')
const geocode = (address, callback) => {
const url = '.places/' +
address + '.json?access_token=pk.eyJ1IjoiYW5kcmV3bWVhZDEiLCJhIjoiY2pvOG8ybW90MDFhazNxcnJ4OTYydzJlOSJ9.njY7HvaalLEVhEOIghPTlw&limit=1'
request({ url: url, json: true }, (error, response) => {
if (error) {
callback('Unable to connect to location services!', undefined)
} else if (response.body.features.length === 0) {
callback('Unable to find location. Try another search.',
undefined)
} else {
callback(undefined, {
latitude: response.body.features[0].center[0],
longitude: response.body.features[0].center[1],
location: response.body.features[0].place_name
})
}
})
}
module.exports = geocode
我希望看到波士顿,它的纬度和经度。
回答如下:在检查features
长度之前,您还可以检查features
是否存在:
else if (response.body.features && response.body.features.length === 0) {
NodeJS:无法读取未定义的属性'length'
[当我在nodejs中运行node app.js时,错误消息显示'无法读取未定义的属性'length'。我已经安装了所有相关的库(例如,请求),并查看了不同的相关帖子。但是,问题仍然存在。
[请您告知我如何解决。非常感谢!
Windows 10家用PCVisual Studio代码
//app.js
const geocode = require('./utils/geocode')
const forecast = require('./utils/forecast')
geocode('Boston', (error, data) => {
console.log('Error', error)
console.log('Data', data)
forecast(data.latitude, data.longitude, (error, data) => {
console.log('Error', error)
console.log('Data', data)
})
})
// forecast.js
const request = require('request')
const forecast = (latitude, longitude, callback) => {
const url =
'/' +
latitude + ',' + longitude
request({ url: url, json: true }, (error, response) => {
if (error) {
callback('Unable to connect to weather service!', undefined)
} else if (response.body.error) {
callback('Unable to find location', undefined)
} else {
callback(undefined, response.body.daily.data[0].summary + ' It is
currently ' + response.body.currently.temperature + ' degress out. There
is a ' + response.body.currently.precipProbability + '% chance of rain.')
}
})
}
module.exports = forecast
// geocode.js
const request = require('request')
const geocode = (address, callback) => {
const url = '.places/' +
address + '.json?access_token=pk.eyJ1IjoiYW5kcmV3bWVhZDEiLCJhIjoiY2pvOG8ybW90MDFhazNxcnJ4OTYydzJlOSJ9.njY7HvaalLEVhEOIghPTlw&limit=1'
request({ url: url, json: true }, (error, response) => {
if (error) {
callback('Unable to connect to location services!', undefined)
} else if (response.body.features.length === 0) {
callback('Unable to find location. Try another search.',
undefined)
} else {
callback(undefined, {
latitude: response.body.features[0].center[0],
longitude: response.body.features[0].center[1],
location: response.body.features[0].place_name
})
}
})
}
module.exports = geocode
我希望看到波士顿,它的纬度和经度。
回答如下:在检查features
长度之前,您还可以检查features
是否存在:
else if (response.body.features && response.body.features.length === 0) {