simple api proxy that queues requests when cached data is out of date.

node-forecast-proxy.js

var request = require('request');
var moment  = require('moment');
var http    = require('http');
var colors  = require('colors');

var latLong = "45.5330,-122.6894";
var apiKey  = "a75c248d7b83806b66b281dd33e96e36";
var url     = 'https://api.forecast.io/forecast';

url += '/' + apiKey + '/' + latLong;

request(url, function (err, apiResponse, body) {
  var appData = {};
  appData.data = JSON.parse(body);
  appData.timeStamp = Date.now();
  
  serverReady(appData);
});

function serverReady (appData) {

  var queueRequest = requestQueue(appData);

  http.createServer(function (clientRequest, myResponse) {
    if (Date.now() - appData.timeStamp > 10000) {
      console.log(timeStamp('yellow') + ' - Queueing request from: ' + clientRequest.headers.host);
      queueRequest(function (body) {
        console.log(timeStamp('red') + ' - Answering queued request from: ' + clientRequest.headers.host);
        myResponse.end(body);
      });
    } else {
      console.log(timeStamp('green') + ' - Request from: ' + clientRequest.headers.host);
      myResponse.end(JSON.stringify(appData.data));
    }
  }).listen(7357);

  console.log('Listening on: 7357');
}

function timeStamp (color) {
  return ('[' + moment(Date.now()).format('hh:mm:ssa') + ']')[color];
}

function requestQueue (appData) {
  var itsOnItsWay = false;
  var callbacks = [];

  return function (cb) {
    callbacks.push(cb);

    if (!itsOnItsWay) { 
      request(url, function (err, apiResponse, body) {
        appData.data = JSON.parse(body);
        appData.timeStamp = Date.now();
        callbacks.forEach(function (cb) {
          cb(body);
        });
        itsOnItsWay = false;
        callbacks = [];
      });
      itsOnItsWay = true;
    } 
  }
}