Nodejs how to do some logic when previous logic were done - node.js

Question

An array[1,2,3,4]take 2 of them and send 2 requests with them;
Once completed take another 2 and create two new requests;
I know I cant do it like below because Nodejs is synchronous;
var request = require('request');
var args=[1,2,3,4];
function chunk(){...}
args = chunk(args,2); //My custom function to split array into chunks
args.forEach(function(value)
{
value.forEach(function(value_value)
{
/***********sent requests**************/
var options = {
method: 'POST',
url: 'http://dev.site/date.php',
formData: {arguments:value_value}
};
request(options, function (error, response, body)
{
if (body=='hello') {
console.log(body);
}
});
/**************************************/
});
});
please Help me

Answer 1

You can use request-promise and q - then chain response:
var request = require('request-promise');
var Q = require('q');
var args=[1,2,3,4];
function chunk(){...}
args = chunk(args,2); //My custom function to split array into chunks
args.forEach(function(value)
{
var result = Q();
args.forEach(function (t) {
result = result.then(request_each.bind(null, value));
});
return result; // result has the final promise (use .then on that)
});
function request_each(value) {
return Q.all(value.forEach(function(value_value)
{
/***********sent requests**************/
var options = {
method: 'POST',
url: 'http://dev.site/date.php',
formData: {arguments:value_value}
};
return request(options);
/**************************************/
}));
}
You can just use q and request (changing the request_each function):
function request_each(value) {
return Q.all(value.forEach(function(value_value)
{
var deferred = Q.defer();
/***********sent requests**************/
var options = {
method: 'POST',
url: 'http://dev.site/date.php',
formData: {arguments:value_value}
};
request(options, function (error, response, body) {
if (body=='hello') {
deferred.resolve(body);
}
});
return deferred.promise;
/**************************************/
}));
}