Demo :: Asynchronous

demo01.js

var fs = require("fs");

fs.readFile("mydata.json", function(err, content) {
    if (err) {
        console.error("Got an error", err);
    } else {
        console.log("Got result");
    }
});
console.log("After call readFile")

demo02.js

var FS = require('fs'),
    request = require('request');

function getResults(pathToFile, callback) {
    FS.readFile(pathToFile, 'utf8', function(err, data) {
        if (err) return callback(err);
        var response1, response2;

        request.post('http://www.thomas-bayer.com/sqlrest/', function(err, response, body) {
            if(err) return callback(err);
            response1 = response;
            next();
        }); 

        request.post('http://www.thomas-bayer.com/sqlrest/', function(err, response, body) {
            if(err) return callback(err);
            response2 = response;
            next();
        });         

        function next(){
            if(response1 && response2){
                callback(null, [response1, response2]);
            }
        }
    });
}

getResults('./www/mydata.json', function(err, content) {
    if (err) {
        console.error("Got an error", err);
    } else {
        console.log("Got result ");
    }
});

demo03.js

asyncCall(function(err, data1){
    if(err) return callback(err);       
    anotherAsyncCall(function(err2, data2){
        if(err2) return calllback(err2);
        oneMoreAsyncCall(function(err3, data3){
            if(err3) return callback(err3);
            // TODO
        });
    });
});

demo04.js

asyncCall()
.then(function(data1){
    // do something...
    return anotherAsyncCall();
})
.then(function(data2){
    // do something...  
    return oneMoreAsyncCall();    
})
.then(function(data3){
   // the third and final async response
})
.fail(function(err) {
   // handle any error resulting from any of the above calls    
})
.done();

demo05.js

var FS = require('fs'),
    Q = require('q');

Q.nfcall(FS.readFile, "mydata.json", "utf-8")
.then(function(data) {      
    console.log('File has been read:', data);
})
.fail(function(err) {
    console.error('Error received:', err);
})
.done();

demo06.js

var FS = require('fs'),
    Q = require('q'),
    request = require('request');

function getResults(pathToFile) {   
    return Q.nfcall(FS.readFile, pathToFile, "utf-8")
    .then(function(repo) {
        var options = { headers: {'User-Agent': 'MyAgent'} }; 
        return [Q.nfcall(request, 'https://api.github.com/repos/'+repo+'/collaborators', options),
                Q.nfcall(request, 'https://api.github.com/repos/'+repo+'/commits', options)];
    })
    .spread(function(collaboratorsRes, commitsRes) {        
        return [collaboratorsRes[1], commitsRes[1]];
    })
    .fail(function(err) {
        console.error(err)
        return err;
    });
}

// actual call
getResults('repos.txt').then(function(responses) {
    console.log("responses=" + responses)
});