如何让node js等待函数执行(即使需要时间），然后执行下一条语句
How to make node js to wait for function to execute (even if it take time) and then execute the next statement
如何使节点js等待函数执行（即使需要时间），然后执行下一条语句。对我来说，问题是for循环首先打印所有url，它不等待require请求函数检查每个url的http响应。它只是打印所有URL。正因为如此，我得到了错误
console.log(dd[i]['loc'][0]);
^
TypeError:无法读取未定义的属性"loc"
我的完整源代码如下
var hapi = require('hapi');
var glue = require('glue');
var joi = require('joi');
var handlebars = require('handlebars');
var strop = require('string');
var inert = require('inert');
var async = require('async');
var poop = require('poop');
var bell = require('bell');
var nconf = require('nconf');
//xml parser starts
var fs = require('fs'),
xml2js = require('xml2js');
var parser = new xml2js.Parser();
fs.readFile('sitemapscene1.xml', function(err, data) {
var count = 0;
var a=0;
var b=0;
var c=0;
var d=0;
var e=0;
var f=0;
var g=0;
var h=0;
//parsing inside url starts
var parseString = require('xml2js').parseString;
parser.parseString(data, function (err, result) {
ff = result;
dd = ff['urlset']['url'];
for (i =0; i< dd.length; i++){
console.log(dd[i]['loc'][0]);
//server reuest and checking
var request = require('request');
request(dd[i]['loc'][0], function (error, response, body) {
if (!error && response.statusCode == 200) {
console.log(dd[i]['loc'][0]);
console.log("This url http response is 200");
count=count+1;
console.log(count);
}
})
}
console.log("Total number of urls in this sitemap");
console.log(dd.length);
});
});
//xml parser ends
My full error code is
Total number of urls in this sitemap
22569
console.log(dd[i]['loc'][0]);
^
TypeError: Cannot read property 'loc' of undefined
at Request._callback
at Request.self.callback
at emitTwo (events.js:87:13)
at Request.emit (events.js:172:7)
at Request.<anonymous>
at emitOne (events.js:77:13)
at Request.emit (events.js:169:7)
at IncomingMessage.<anonymous>
at emitNone (events.js:72:20)
at IncomingMessage.emit (events.js:166:7)
我的实际完整代码
var hapi = require('hapi');
var glue = require('glue');
var joi = require('joi');
var handlebars = require('handlebars');
var strop = require('string');
var inert = require('inert');
var async = require('async');
var poop = require('poop');
var bell = require('bell');
var nconf = require('nconf');
var async = require('async');
//xml parser starts
var fs = require('fs'),
xml2js = require('xml2js');
var parser = new xml2js.Parser();
fs.readFile('sitemapscene1.xml', function(err, data) {
var count = 0;
var a=0;
var b=0;
var c=0;
var d=0;
var e=0;
var f=0;
var g=0;
var h=0;
//parsing inside url starts
var parseString = require('xml2js').parseString;
parser.parseString(data, function (err, result) {
ff = result;
dd = ff['urlset']['url'];
console.log("Total number of urls in this sitemap");
console.log(dd.length);
for (i =0; i< dd.length; i++){
console.log(dd[i]['loc'][0]);
//sending to server to get response
var request = require("request");
request(dd[i]['loc'][0], function(error, response, body) {
//console.log(response.statuscode);
if (!error && response.statusCode == 200) {
count=count+1;
console.log("Number of pages with responese.statuscode 200 is");
console.log(count);
var ddddd = "Number of pages with responese.statuscode 200 is " + count + " " + dd[i]['loc'][0]
// output is wriiten in output.txt file start here
fs = require('fs');
fs.writeFile('output.txt', ddddd, function (err) {
if (err) return console.log(err);
console.log('Hello World > output.txt');
});
// output is wriiten in output.txt file ends here
} else if ( error && response.statusCode == 400 ) {
a=a+1;
console.log("Number of pages with responese.statuscode 400 is");
console.log(a);
var ddddd = "Number of pages with responese.statuscode 200 is " + count + " " + dd[i]['loc'][0]
// output is wriiten in output.txt file start here
fs = require('fs');
fs.writeFile('output.txt', ddddd, function (err) {
if (err) return console.log(err);
console.log('Hello World > output.txt');
});
// output is wriiten in output.txt file ends here
}else if ( error && response.statusCode == 402 ) {
b=b+1;
console.log("Number of pages with responese.statuscode 402 is");
console.log(b);
var ddddd = "Number of pages with responese.statuscode 200 is " + count + " " + dd[i]['loc'][0]
// output is wriiten in output.txt file start here
fs = require('fs');
fs.writeFile('output.txt', ddddd, function (err) {
if (err) return console.log(err);
console.log('Hello World > output.txt');
});
// output is wriiten in output.txt file ends here
}else if ( error && response.statusCode == 403 ) {
c=c+1;
console.log("Number of pages with responese.statuscode 403 is");
console.log(c);
var ddddd = "Number of pages with responese.statuscode 200 is " + count + " " + dd[i]['loc'][0]
// output is wriiten in output.txt file start here
fs = require('fs');
fs.writeFile('output.txt', ddddd, function (err) {
if (err) return console.log(err);
console.log('Hello World > output.txt');
});
// output is wriiten in output.txt file ends here
}else if ( error && response.statusCode == 404 ) {
d=d+1;
console.log("Number of pages with responese.statuscode 404 is");
console.log(d);
}else if ( error && response.statusCode == 500 ) {
e=e+1;
console.log("Number of pages with responese.statuscode 500 is");
console.log(e);
var ddddd = "Number of pages with responese.statuscode 200 is " + count + " " + dd[i]['loc'][0]
// output is wriiten in output.txt file start here
fs = require('fs');
fs.writeFile('output.txt', ddddd, function (err) {
if (err) return console.log(err);
console.log('Hello World > output.txt');
});
// output is wriiten in output.txt file ends here
}else if ( error && response.statusCode == 502 ) {
f=f+1;
console.log("Number of pages with responese.statuscode 502 is");
console.log(f);
var ddddd = "Number of pages with responese.statuscode 200 is " + count + " " + dd[i]['loc'][0]
// output is wriiten in output.txt file start here
fs = require('fs');
fs.writeFile('output.txt', ddddd, function (err) {
if (err) return console.log(err);
console.log('Hello World > output.txt');
});
// output is wriiten in output.txt file ends here
}else if ( error && response.statusCode == 504 ) {
g=g+1;
console.log("Number of pages with responese.statuscode 504 is");
console.log(g);
var ddddd = "Number of pages with responese.statuscode 200 is " + count + " " + dd[i]['loc'][0]
// output is wriiten in output.txt file start here
fs = require('fs');
fs.writeFile('output.txt', ddddd, function (err) {
if (err) return console.log(err);
console.log('Hello World > output.txt');
});
// output is wriiten in output.txt file ends here
} else {
h=h+1;
console.log("Number of pages with error is");
console.log(h);
var ddddd = "Number of pages with responese.statuscode 200 is " + count + " " + dd[i]['loc'][0]
// output is wriiten in output.txt file start here
fs = require('fs');
fs.writeFile('output.txt', ddddd, function (err) {
if (err) return console.log(err);
console.log('Hello World > output.txt');
});
// output is wriiten in output.txt file ends here
}
});
}
//console.log("Number of urls,in this site map");
//console.log(dd.length); //number of urls
});
});
//xml parser ends
这是导致服务器崩溃的代码，我认为我在代码中犯了错误，而不是服务器内存不足
var hapi = require('hapi');
var glue = require('glue');
var joi = require('joi');
var handlebars = require('handlebars');
var strop = require('string');
var inert = require('inert');
var async = require('async');
var poop = require('poop');
var bell = require('bell');
var nconf = require('nconf');
var async = require('async');
//xml parser starts
var fs = require('fs'),
xml2js = require('xml2js');
var parser = new xml2js.Parser();
fs.readFile('sitemapscene1.xml', function(err, data) {
var count = 0;
var a=0;
var b=0;
var c=0;
var d=0;
var e=0;
var f=0;
var g=0;
var h=0;
//parsing inside url starts
var parseString = require('xml2js').parseString;
parser.parseString(data, function (err, result) {
ff = result;
dd = ff['urlset']['url'];
for (i =0; i< dd.length; i++){
console.log(dd[i]['loc'][0]);
//server reuest and checking
var asyncRequests = [];
var request = require('request');
dd.forEach(function(ddElement){
asyncRequests.push(function(callback){
request(ddElement.loc[0], function(error, response, body) {
if (!error && response.statusCode == 200) {
return callback(null, 1);
}
callback();
});
});
});
async.parallel(asyncRequests, function afterStatement(err, results){
var count = 0;
for (var i = 0; i < results.length; i ++){
if (results[i]){
count += results[i];
}
}
});
}
console.log("Total number of urls in this sitemap");
console.log(dd.length);
});
});
//xml parser ends
您需要异步，为什么不使用它呢？
var asyncRequests = [];
var request = require('request');
dd.forEach(function(ddElement){
asyncRequests.push(function(callback){
request(ddElement.loc[0], function(error, response, body) {
if (!error && response.statusCode == 200) {
return callback(null, 1);
}
callback();
});
});
});
async.parallel(asyncRequests, function afterStatement(err, results){
var count = 0;
for (var i = 0; i < results.length; i ++){
// I don't remember if something is send with callback(), so check data
if (results[i]){
count += results[i];
}
}
});
下次请发送可读且缩进的代码。
编辑：如果你想计数，获取一个与路由相关的结果的对象（我认为ddElement.loc[0]是路由）：
var asyncRequests = [];
var request = require('request');
dd.forEach(function(ddElement){
asyncRequests.push(function(callback){
request(ddElement.loc[0], function(error, response, body) {
callback(error, {
statusCode : response.statusCode,
route : ddElement.loc[0]
});
});
});
});
async.parallel(asyncRequests, function afterStatement(err, results){
if (err){
console.error(err);
}
console.log(results);
});
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