Javascript 在函数外使用变量
首先,我要说的是,我确实在努力学习node,但遇到了一些困难。我正在构建一个超级简单的天气应用程序,调用API,然后我想返回数据 但我不知道为什么它不会将这些数据返回到控制台Javascript 在函数外使用变量,javascript,node.js,Javascript,Node.js,首先,我要说的是,我确实在努力学习node,但遇到了一些困难。我正在构建一个超级简单的天气应用程序,调用API,然后我想返回数据 但我不知道为什么它不会将这些数据返回到控制台 var request = require('request'); request('https://api.forecast.io/forecast/{API KEY}/42.47994,-83.13040', function (error, response, body) { if (!error &
var request = require('request');
request('https://api.forecast.io/forecast/{API KEY}/42.47994,-83.13040', function (error, response, body) {
if (!error && response.statusCode == 200) {
//var info = JSON.parse(body);
var jsonObject = JSON.parse(body);
var summary = jsonObject.currently.summary;
var temp = jsonObject.currently.temperature;
var realFeel = jsonObject.currently.apparentTemperature;
var summary2 = jsonObject.hourly.summary;
var max = jsonObject.daily.data[0].temperatureMax;
var min = jsonObject.daily.data[0].temperatureMin;
}
})
console.log('Todays forecast ' + summary2 + ' With a current Tempature of ' + temp + '. But feels like ' +realFeel + ' With a high of '+max+' and a low of '+min);
所有变量都是回调函数的局部变量。将console.log语句移动到函数中
var request = require('request');
request('https://api.forecast.io/forecast/{API KEY}/42.47994,-83.13040', function (error, response, body) {
if (!error && response.statusCode == 200) {
//var info = JSON.parse(body);
var jsonObject = JSON.parse(body);
var summary = jsonObject.currently.summary;
var temp = jsonObject.currently.temperature;
var realFeel = jsonObject.currently.apparentTemperature;
var summary2 = jsonObject.hourly.summary;
var max = jsonObject.daily.data[0].temperatureMax;
var min = jsonObject.daily.data[0].temperatureMin;
console.log('Todays forecast ' + summary2 + ' With a current Tempature of ' + temp + '. But feels like ' +realFeel + ' With a high of '+max+' and a low of '+min);
}
})
如果希望所有变量都是全局变量(坏主意),请从回调函数中删除var
语句:
(function (){ // add this line
var request = require('request');
var summary, temp, realFeel, summary2, max, min;
request('https://api.forecast.io/forecast/{API KEY}/42.47994,-83.13040', function (error, response, body) {
if (!error && response.statusCode == 200) {
//var info = JSON.parse(body);
var jsonObject = JSON.parse(body);
summary = jsonObject.currently.summary;
temp = jsonObject.currently.temperature;
realFeel = jsonObject.currently.apparentTemperature;
summary2 = jsonObject.hourly.summary;
max = jsonObject.daily.data[0].temperatureMax;
min = jsonObject.daily.data[0].temperatureMin;
console.log('Todays forecast ' + summary2 + ' With a current Tempature of ' + temp + '. But feels like ' +realFeel + ' With a high of '+max+' and a low of '+min);
}
});
}()); // and this line to avoid global variables
但是你仍然需要一段代码来显示你的天气摘要。post中回调函数外部的console.log将在数据从forecast服务返回之前运行。简而言之,必须将console.log放在回调函数中
var request = require('request');
request('https://api.forecast.io/forecast/{API KEY}/42.47994,-83.13040', function (error, response, body) {
if (!error && response.statusCode == 200) {
//var info = JSON.parse(body);
var jsonObject = JSON.parse(body);
var summary = jsonObject.currently.summary;
var temp = jsonObject.currently.temperature;
var realFeel = jsonObject.currently.apparentTemperature;
var summary2 = jsonObject.hourly.summary;
var max = jsonObject.daily.data[0].temperatureMax;
var min = jsonObject.daily.data[0].temperatureMin;
console.log('Todays forecast ' + summary2 + ' With a current Tempature of ' + temp + '. But feels like ' +realFeel + ' With a high of '+max+' and a low of '+min);
}
})
这个答案直接回答了你的具体问题。请理解创建。所有变量都是回调函数的本地变量。将console.log语句移动到函数中
var request = require('request');
request('https://api.forecast.io/forecast/{API KEY}/42.47994,-83.13040', function (error, response, body) {
if (!error && response.statusCode == 200) {
//var info = JSON.parse(body);
var jsonObject = JSON.parse(body);
var summary = jsonObject.currently.summary;
var temp = jsonObject.currently.temperature;
var realFeel = jsonObject.currently.apparentTemperature;
var summary2 = jsonObject.hourly.summary;
var max = jsonObject.daily.data[0].temperatureMax;
var min = jsonObject.daily.data[0].temperatureMin;
console.log('Todays forecast ' + summary2 + ' With a current Tempature of ' + temp + '. But feels like ' +realFeel + ' With a high of '+max+' and a low of '+min);
}
})
如果希望所有变量都是全局变量(坏主意),请从回调函数中删除var
语句:
(function (){ // add this line
var request = require('request');
var summary, temp, realFeel, summary2, max, min;
request('https://api.forecast.io/forecast/{API KEY}/42.47994,-83.13040', function (error, response, body) {
if (!error && response.statusCode == 200) {
//var info = JSON.parse(body);
var jsonObject = JSON.parse(body);
summary = jsonObject.currently.summary;
temp = jsonObject.currently.temperature;
realFeel = jsonObject.currently.apparentTemperature;
summary2 = jsonObject.hourly.summary;
max = jsonObject.daily.data[0].temperatureMax;
min = jsonObject.daily.data[0].temperatureMin;
console.log('Todays forecast ' + summary2 + ' With a current Tempature of ' + temp + '. But feels like ' +realFeel + ' With a high of '+max+' and a low of '+min);
}
});
}()); // and this line to avoid global variables
但是你仍然需要一段代码来显示你的天气摘要。post中回调函数外部的console.log将在数据从forecast服务返回之前运行。简而言之,必须将console.log放在回调函数中
var request = require('request');
request('https://api.forecast.io/forecast/{API KEY}/42.47994,-83.13040', function (error, response, body) {
if (!error && response.statusCode == 200) {
//var info = JSON.parse(body);
var jsonObject = JSON.parse(body);
var summary = jsonObject.currently.summary;
var temp = jsonObject.currently.temperature;
var realFeel = jsonObject.currently.apparentTemperature;
var summary2 = jsonObject.hourly.summary;
var max = jsonObject.daily.data[0].temperatureMax;
var min = jsonObject.daily.data[0].temperatureMin;
console.log('Todays forecast ' + summary2 + ' With a current Tempature of ' + temp + '. But feels like ' +realFeel + ' With a high of '+max+' and a low of '+min);
}
})
这个答案直接回答了你的具体问题。请理解创建。所有变量都是回调函数的本地变量。将console.log语句移动到函数中
var request = require('request');
request('https://api.forecast.io/forecast/{API KEY}/42.47994,-83.13040', function (error, response, body) {
if (!error && response.statusCode == 200) {
//var info = JSON.parse(body);
var jsonObject = JSON.parse(body);
var summary = jsonObject.currently.summary;
var temp = jsonObject.currently.temperature;
var realFeel = jsonObject.currently.apparentTemperature;
var summary2 = jsonObject.hourly.summary;
var max = jsonObject.daily.data[0].temperatureMax;
var min = jsonObject.daily.data[0].temperatureMin;
console.log('Todays forecast ' + summary2 + ' With a current Tempature of ' + temp + '. But feels like ' +realFeel + ' With a high of '+max+' and a low of '+min);
}
})
如果希望所有变量都是全局变量(坏主意),请从回调函数中删除var
语句:
(function (){ // add this line
var request = require('request');
var summary, temp, realFeel, summary2, max, min;
request('https://api.forecast.io/forecast/{API KEY}/42.47994,-83.13040', function (error, response, body) {
if (!error && response.statusCode == 200) {
//var info = JSON.parse(body);
var jsonObject = JSON.parse(body);
summary = jsonObject.currently.summary;
temp = jsonObject.currently.temperature;
realFeel = jsonObject.currently.apparentTemperature;
summary2 = jsonObject.hourly.summary;
max = jsonObject.daily.data[0].temperatureMax;
min = jsonObject.daily.data[0].temperatureMin;
console.log('Todays forecast ' + summary2 + ' With a current Tempature of ' + temp + '. But feels like ' +realFeel + ' With a high of '+max+' and a low of '+min);
}
});
}()); // and this line to avoid global variables
但是你仍然需要一段代码来显示你的天气摘要。post中回调函数外部的console.log将在数据从forecast服务返回之前运行。简而言之,必须将console.log放在回调函数中
var request = require('request');
request('https://api.forecast.io/forecast/{API KEY}/42.47994,-83.13040', function (error, response, body) {
if (!error && response.statusCode == 200) {
//var info = JSON.parse(body);
var jsonObject = JSON.parse(body);
var summary = jsonObject.currently.summary;
var temp = jsonObject.currently.temperature;
var realFeel = jsonObject.currently.apparentTemperature;
var summary2 = jsonObject.hourly.summary;
var max = jsonObject.daily.data[0].temperatureMax;
var min = jsonObject.daily.data[0].temperatureMin;
console.log('Todays forecast ' + summary2 + ' With a current Tempature of ' + temp + '. But feels like ' +realFeel + ' With a high of '+max+' and a low of '+min);
}
})
这个答案直接回答了你的具体问题。请理解创建。所有变量都是回调函数的本地变量。将console.log语句移动到函数中
var request = require('request');
request('https://api.forecast.io/forecast/{API KEY}/42.47994,-83.13040', function (error, response, body) {
if (!error && response.statusCode == 200) {
//var info = JSON.parse(body);
var jsonObject = JSON.parse(body);
var summary = jsonObject.currently.summary;
var temp = jsonObject.currently.temperature;
var realFeel = jsonObject.currently.apparentTemperature;
var summary2 = jsonObject.hourly.summary;
var max = jsonObject.daily.data[0].temperatureMax;
var min = jsonObject.daily.data[0].temperatureMin;
console.log('Todays forecast ' + summary2 + ' With a current Tempature of ' + temp + '. But feels like ' +realFeel + ' With a high of '+max+' and a low of '+min);
}
})
如果希望所有变量都是全局变量(坏主意),请从回调函数中删除var
语句:
(function (){ // add this line
var request = require('request');
var summary, temp, realFeel, summary2, max, min;
request('https://api.forecast.io/forecast/{API KEY}/42.47994,-83.13040', function (error, response, body) {
if (!error && response.statusCode == 200) {
//var info = JSON.parse(body);
var jsonObject = JSON.parse(body);
summary = jsonObject.currently.summary;
temp = jsonObject.currently.temperature;
realFeel = jsonObject.currently.apparentTemperature;
summary2 = jsonObject.hourly.summary;
max = jsonObject.daily.data[0].temperatureMax;
min = jsonObject.daily.data[0].temperatureMin;
console.log('Todays forecast ' + summary2 + ' With a current Tempature of ' + temp + '. But feels like ' +realFeel + ' With a high of '+max+' and a low of '+min);
}
});
}()); // and this line to avoid global variables
但是你仍然需要一段代码来显示你的天气摘要。post中回调函数外部的console.log将在数据从forecast服务返回之前运行。简而言之,必须将console.log放在回调函数中
var request = require('request');
request('https://api.forecast.io/forecast/{API KEY}/42.47994,-83.13040', function (error, response, body) {
if (!error && response.statusCode == 200) {
//var info = JSON.parse(body);
var jsonObject = JSON.parse(body);
var summary = jsonObject.currently.summary;
var temp = jsonObject.currently.temperature;
var realFeel = jsonObject.currently.apparentTemperature;
var summary2 = jsonObject.hourly.summary;
var max = jsonObject.daily.data[0].temperatureMax;
var min = jsonObject.daily.data[0].temperatureMin;
console.log('Todays forecast ' + summary2 + ' With a current Tempature of ' + temp + '. But feels like ' +realFeel + ' With a high of '+max+' and a low of '+min);
}
})
这个答案直接回答了你的具体问题。请理解创建。节点是一个异步服务器。当您执行要阻止的请求时,节点引擎将继续执行以下代码。您正在向请求模块传递回调,但您的console.log会在请求被触发后立即执行,然后返回结果 您要做的是将代码放在回调函数中使用数据的位置
var request = require('request');
request('https://api.forecast.io/forecast/{API KEY}/42.47994,-83.13040', function (error, response, body) {
if (!error && response.statusCode == 200) {
//var info = JSON.parse(body);
var jsonObject = JSON.parse(body);
var summary = jsonObject.currently.summary;
var temp = jsonObject.currently.temperature;
var realFeel = jsonObject.currently.apparentTemperature;
var summary2 = jsonObject.hourly.summary;
var max = jsonObject.daily.data[0].temperatureMax;
var min = jsonObject.daily.data[0].temperatureMin;
console.log('Todays forecast ' + summary2 + ' With a current Tempature of ' + temp + '. But feels like ' +realFeel + ' With a high of '+max+' and a low of '+min);
}
})
您也不应该忽略错误
var request = require('request');
request('https://api.forecast.io/forecast/{API KEY}/42.47994,-83.13040', function (error, response, body) {
if (error) throw error;
if (response.statusCode != 200) return console.log('Invalid status code: '+response.statusCode)
var jsonObject = JSON.parse(body);
var summary = jsonObject.currently.summary;
var temp = jsonObject.currently.temperature;
var realFeel = jsonObject.currently.apparentTemperature;
var summary2 = jsonObject.hourly.summary;
var max = jsonObject.daily.data[0].temperatureMax;
var min = jsonObject.daily.data[0].temperatureMin;
console.log('Todays forecast ' + summary2 + ' With a current Tempature of ' + temp + '. But feels like ' +realFeel + ' With a high of '+max+' and a low of '+min);
});
节点是一个异步服务器。当您执行要阻止的请求时,节点引擎将继续执行以下代码。您正在向请求模块传递回调,但您的console.log会在请求被触发后立即执行,然后返回结果 您要做的是将代码放在回调函数中使用数据的位置
var request = require('request');
request('https://api.forecast.io/forecast/{API KEY}/42.47994,-83.13040', function (error, response, body) {
if (!error && response.statusCode == 200) {
//var info = JSON.parse(body);
var jsonObject = JSON.parse(body);
var summary = jsonObject.currently.summary;
var temp = jsonObject.currently.temperature;
var realFeel = jsonObject.currently.apparentTemperature;
var summary2 = jsonObject.hourly.summary;
var max = jsonObject.daily.data[0].temperatureMax;
var min = jsonObject.daily.data[0].temperatureMin;
console.log('Todays forecast ' + summary2 + ' With a current Tempature of ' + temp + '. But feels like ' +realFeel + ' With a high of '+max+' and a low of '+min);
}
})
您也不应该忽略错误
var request = require('request');
request('https://api.forecast.io/forecast/{API KEY}/42.47994,-83.13040', function (error, response, body) {
if (error) throw error;
if (response.statusCode != 200) return console.log('Invalid status code: '+response.statusCode)
var jsonObject = JSON.parse(body);
var summary = jsonObject.currently.summary;
var temp = jsonObject.currently.temperature;
var realFeel = jsonObject.currently.apparentTemperature;
var summary2 = jsonObject.hourly.summary;
var max = jsonObject.daily.data[0].temperatureMax;
var min = jsonObject.daily.data[0].temperatureMin;
console.log('Todays forecast ' + summary2 + ' With a current Tempature of ' + temp + '. But feels like ' +realFeel + ' With a high of '+max+' and a low of '+min);
});
节点是一个异步服务器。当您执行要阻止的请求时,节点引擎将继续执行以下代码。您正在向请求模块传递回调,但您的console.log会在请求被触发后立即执行,然后返回结果 您要做的是将代码放在回调函数中使用数据的位置
var request = require('request');
request('https://api.forecast.io/forecast/{API KEY}/42.47994,-83.13040', function (error, response, body) {
if (!error && response.statusCode == 200) {
//var info = JSON.parse(body);
var jsonObject = JSON.parse(body);
var summary = jsonObject.currently.summary;
var temp = jsonObject.currently.temperature;
var realFeel = jsonObject.currently.apparentTemperature;
var summary2 = jsonObject.hourly.summary;
var max = jsonObject.daily.data[0].temperatureMax;
var min = jsonObject.daily.data[0].temperatureMin;
console.log('Todays forecast ' + summary2 + ' With a current Tempature of ' + temp + '. But feels like ' +realFeel + ' With a high of '+max+' and a low of '+min);
}
})
您也不应该忽略错误
var request = require('request');
request('https://api.forecast.io/forecast/{API KEY}/42.47994,-83.13040', function (error, response, body) {
if (error) throw error;
if (response.statusCode != 200) return console.log('Invalid status code: '+response.statusCode)
var jsonObject = JSON.parse(body);
var summary = jsonObject.currently.summary;
var temp = jsonObject.currently.temperature;
var realFeel = jsonObject.currently.apparentTemperature;
var summary2 = jsonObject.hourly.summary;
var max = jsonObject.daily.data[0].temperatureMax;
var min = jsonObject.daily.data[0].temperatureMin;
console.log('Todays forecast ' + summary2 + ' With a current Tempature of ' + temp + '. But feels like ' +realFeel + ' With a high of '+max+' and a low of '+min);
});
节点是一个异步服务器。当您执行要阻止的请求时,节点引擎将继续执行以下代码。您正在向请求模块传递回调,但您的console.log会在请求被触发后立即执行,然后返回结果 您要做的是将代码放在回调函数中使用数据的位置
var request = require('request');
request('https://api.forecast.io/forecast/{API KEY}/42.47994,-83.13040', function (error, response, body) {
if (!error && response.statusCode == 200) {
//var info = JSON.parse(body);
var jsonObject = JSON.parse(body);
var summary = jsonObject.currently.summary;
var temp = jsonObject.currently.temperature;
var realFeel = jsonObject.currently.apparentTemperature;
var summary2 = jsonObject.hourly.summary;
var max = jsonObject.daily.data[0].temperatureMax;
var min = jsonObject.daily.data[0].temperatureMin;
console.log('Todays forecast ' + summary2 + ' With a current Tempature of ' + temp + '. But feels like ' +realFeel + ' With a high of '+max+' and a low of '+min);
}
})
您也不应该忽略错误
var request = require('request');
request('https://api.forecast.io/forecast/{API KEY}/42.47994,-83.13040', function (error, response, body) {
if (error) throw error;
if (response.statusCode != 200) return console.log('Invalid status code: '+response.statusCode)
var jsonObject = JSON.parse(body);
var summary = jsonObject.currently.summary;
var temp = jsonObject.currently.temperature;
var realFeel = jsonObject.currently.apparentTemperature;
var summary2 = jsonObject.hourly.summary;
var max = jsonObject.daily.data[0].temperatureMax;
var min = jsonObject.daily.data[0].temperatureMin;
console.log('Todays forecast ' + summary2 + ' With a current Tempature of ' + temp + '. But feels like ' +realFeel + ' With a high of '+max+' and a low of '+min);
});
问题是,当您使用
var
声明变量时,您将其范围声明为您所在的函数。如果您使用的名称没有使用var声明,它将在全局“窗口”范围中查找它们
在回调函数中删除var关键字,该函数应该改变全局范围 问题在于,当您使用
var
声明变量时,您将其范围声明为您所在的函数。如果您使用的名称没有使用var声明,它将在全局“窗口”范围中查找它们
在回调函数中删除var关键字,该函数应该改变全局范围 问题在于,当您使用
var
声明变量时,您将其范围声明为您所在的函数。如果您使用的名称没有使用var声明,它将在全局“窗口”范围中查找它们
在回调函数中删除var关键字,该函数应该改变全局范围 问题在于,当您使用
var
声明变量时,您将其范围声明为您所在的函数。如果您使用的名称没有使用var声明,它将在全局“窗口”范围中查找它们
在回调函数中删除var关键字,该函数应该改变globa