2017-02-11 74 views
1

我正在使用NodeJS进行事件捕获。所有的电话都将来到getme功能。从这个函数我打电话getUserLocation()函数返回地理位置基于IP。如何根据此值更新全局变量?Node JS如何从函数的回调函数中访问全局变量?

var getClientAddress = function (req) { 
return (req.get('x-forwarded-for') || '').split(',')[0] || req.connection.remoteAddress; 
} 

var getClientLocation = function (ipaddress, callback) { 
    freegeoip.getLocation(ipaddress, function(err, location) { 
     if (err) throw err; 
     return callback(location); 
    }); 
} 

var store = [{'hello': 'world', 'country': 'India', 'City': 'Indupur'}]; 

for (eve=0;eve<store.length;eve++){ 
if(!store[eve].lat){ 
     clientIp = getClientAddress(req); 
     getClientLocation("XXX:XX:XX:XXX", function(resp) { 
      console.log(resp); 
      store[eve].country = store[eve].country || resp.country_name; 
      store[eve].region = store[eve].region || resp.region_name; 
      store[eve].city = store[eve].city || resp.city; 
      store[eve].lat = store[eve].lat || resp.latitude; 
      store[eve].lng = store[eve].lng || resp.longitude; 
     }); 

    } 

但商店不可访问。它是未定义的。我如何更新商店?

实际代码: 下面是实际的代码:

https://github.com/Gowtham95india/CapVengine/blob/master/server.js

以下是错误消息:

Server started! At http://localhost:8080 
Redis started! Ready to perform 
{ e: '[{"device_id":"dsfkdjf-dsfdls-fejfskj-e2oiej2j3jf","user_id":2124,"email":"[email protected]","event_properties":{"utm_source":"HelloWorld"}, "lat":""}]', 
    v: 2 } 
2017-02-11T09:02:10.838Z 


{ ip: '121.244.122.142', 
    country_code: 'IN', 
    country_name: 'India', 
    region_code: 'MH', 
    region_name: 'Maharashtra', 
    city: 'Phursungi', 
    zip_code: '412308', 
    time_zone: 'Asia/Kolkata', 
    latitude: 18.4667, 
    longitude: 73.9833, 
    metro_code: 0 } 
/Users/GowthamSai/Documents/repo/capeve/server.js:111 
       store[eve].country = store[eve].country || resp.country_name; 
              ^

TypeError: Cannot read property 'country' of undefined 
    at /Users/GowthamSai/Documents/repo/capeve/server.js:111:48 
    at /Users/GowthamSai/Documents/repo/capeve/server.js:36:16 
    at Request._callback (/Users/GowthamSai/Documents/repo/capeve/node_modules/node-freegeoip/lib/freegeoip.js:25:16) 
    at Request.self.callback (/Users/GowthamSai/Documents/repo/capeve/node_modules/request/request.js:187:22) 
    at emitTwo (events.js:106:13) 
    at Request.emit (events.js:191:7) 
    at Request.<anonymous> (/Users/GowthamSai/Documents/repo/capeve/node_modules/request/request.js:1048:10) 
    at emitOne (events.js:96:13) 
    at Request.emit (events.js:188:7) 
    at IncomingMessage.<anonymous> (/Users/GowthamSai/Documents/repo/capeve/node_modules/request/request.js:969:12) 
    at emitNone (events.js:91:20) 
    at IncomingMessage.emit (events.js:185:7) 
    at endReadableNT (_stream_readable.js:974:12) 
    at _combinedTickCallback (internal/process/next_tick.js:74:11) 
    at process._tickCallback (internal/process/next_tick.js:98:9) 
+0

一般定义JavaScript中的全局变量,函数声明过程中不使用关键字'var'。尝试在商店变量的声明期间省略关键字'var'。 –

+0

你看到了哪个错误? – oklas

+0

@SiddharthSrinivasan - 这是可怕的建议。应该明确声明Javascript中的所有变量。您应该将其声明在期望的范围内。隐式或偶然的全局变量是一个可怕的想法,事实上,当在严格模式下运行时(编程的安全方式)会变成错误。 – jfriend00

回答

1

你的问题是不是访问store。该全局变量已定义。

您的问题正在访问store[eve],因为您从未定义过

您可以直接尝试阅读store[eve].lat,而无需分配任何东西给store[eve](例如使用store[eve] = store[eve] || {})。


你也有一对夫妇的其他问题,这是问题的根源,这是由解释说:

+0

如果我没有错,里面for循环前夕持有索引位置的值。所以,store [eve]将成为第一次迭代的第一个存储元素。如我错了请纠正我。 –

+0

@ 7H3IN5ID3R - 你错了。请参阅答案末尾的两个链接。在回调触发之前,'eve'会被更新。 – Quentin

+0

是的,你是对的。前夕值变成1. store [1],这明显是未定义的。感谢您指出错误。在这种情况下,这将是纠正这种情况的好方法吗? –

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