Node.js + bluebird + JSON. JSON is not valid after modification - json

Question

Trying to get API data.
I have problem with creating valid JSON after modification.
Data should looks like this: [{"1"},{"2"},{"3"}, ... ,{201},{202},{203}, ...]
but now: [{"1"},{"2"},{"3"}, ...],[{"201"},{"202"},{"203"}, ...]
Where is my mistake?
var Promise = require("bluebird");
var request = require('bluebird').promisifyAll(require('request'));
var fs = Promise.promisifyAll(require('fs'));
var ladders = {"hardcore":"hardcore", "standard":"standard"};
function getJSONsync(urls) {
var ladder = [];
Promise.map(urls, function(url) {
return request
.getAsync(url)
.spread(function (res, body) {
if (res.statusCode != 200) {
throw new Error('Unsuccessful attempt. Code: '+ res.statusCode);
}
return JSON.stringify(ladder.concat(JSON.parse(body).entries), "", 4);
})
.catch(console.error);
},{ concurrency: 10 })
.then(function(arr) {
fs.writeFileAsync('file.json', arr);
})
}
function setUrls(ladderName, offset, limit) {
var arr = [];
while(offset < 15000 ) {
arr.push('http://api.pathofexile.com/ladders/'+ladderName+'?offset='+offset+'&limit='+limit);
offset = offset + 200;
}
return arr;
}
getJSONsync(setUrls(ladders.hardcore, 0, 200));
Thx for help.
Sorry for my Eng.
Finally:
var Promise = require("bluebird");
var request = require('bluebird').promisifyAll(require('request'));
var fs = Promise.promisifyAll(require('fs'));
var ladders = {"hardcore":"hardcore","standard":"standard"};
function getJSONsync(urls) {
Promise.map(urls, function(url) {
return request
.getAsync(url)
.spread(function (res, body) {
if (res.statusCode != 200) {
throw new Error('Unsuccessful attempt. Code: '+ res.statusCode);
}
return JSON.parse(body).entries;
})
.catch(console.error);
},{ concurrency: 10 })
.reduce(function(a, b) { return a.concat(b) })
.then(function(arr) {
fs.writeFileAsync('file.json', JSON.stringify(arr, "", 4));
console.log(arr.length);
})
}
function setUrls(ladder, offset, limit) {
var arr = [];
while(offset < 15000 ) {
arr.push('http://api.pathofexile.com/ladders/'+ladder+'?offset='+offset+'&limit='+limit);
offset = offset + 200;
}
return arr;
}
getJSONsync(setUrls(ladders.hardcore, 0, 200));

Answer 1

Promise.map returns an array, so when you do ladder.concat you return another array, so it becomes [[{"1"}], [{"1", "2"}]
You should just remove concat:
return JSON.stringify(JSON.parse(body).entries, "", 4);
But if you want to use variable ladder you may ladder.push(JSON.stringify(JSON.parse(body).entries, "", 4)) and use it instead of arr returned variable