[英]How to use function callbacks in Nodejs with xml2js
我正在使用xml2js來解析Nodejs中的XML文檔。
XML文件是遠程托管的,因此我使用Node.js http請求來獲取xml數據,然后使用xml2js對其進行解析,如下所示:
var parser = new xml2js.Parser();
function getValue(){
var options = {
hostname: myHost,
path: myPath,
method: 'GET',
headers: {
'Authorization': myAuthString
}
};
var req = http.request(options, function(res) {
res.on('data', function (response) {
parser.parseString(response);
});
});
req.end();
}
parser.on('end', function(result) {
// Output the distribution plans to console
eyes.inspect(result);
// Get the value that I want to use
var returnThis = result['myKey'];
});
上面的代碼有效,當http請求接收到“ data”事件時,我獲取XML數據,然后xml2js解析器解析XML,並在解析的“ end”事件中獲取數據。
我的問題是,如何使用回調將“ returnThis”變量值返回給getValue函數?
例如,如果我要從XML中檢索人名,則希望此方法有效:
console.log("The returned name is: " + getValue());
任何建議將不勝感激! TIA!
請嘗試以下操作:
function getValue(callback){
var options = {
hostname: myHost,
path: myPath,
method: 'GET',
headers: {
'Authorization': myAuthString
}
};
var req = http.request(options, function(res) {
var parser = new xml2js.Parser();
parser.on('end', function(result) {
// Output the distribution plans to console
eyes.inspect(result);
callback(null, result['myKey'])
});
res.on('data', function (response) {
parser.parseString(response);
});
});
req.end();
}
要使用您的函數,您將需要像這樣調用您的函數:
getValue(function(err, res){
// res should equal myKey
console.log(res)
})
事件示例
var emitter = require('events').EventEmitter,
parseEmitter = new emitter();
function getValue(trigger){
var options = {
hostname: myHost,
path: myPath,
method: 'GET',
headers: {
'Authorization': myAuthString
}
};
var req = http.request(options, function(res) {
var parser = new xml2js.Parser();
parser.on('end', function(result) {
// Output the distribution plans to console
eyes.inspect(result);
callback(null, result['myKey'])
});
res.on('data', function (response) {
parser.parseString(response);
});
});
parser.on('end', function(result) {
// Output the distribution plans to console
eyes.inspect(result);
// Get the value that I want to use
var returnThis = result['myKey'];
trigger.emit('log', returnThis);
});
req.end();
}
parseEmitter.on('log', function(value) {
console.log('The return name is '+value);
}
getValue(parseEmitter);
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