ticker with queue

test-queue.js

var fs       = require('fs');
var async    = require('async');



function updateJson(ticker, value, cb) {
    async.waterfall([
    function(next){
      fs.readFile('stocktest.json', next);
    },
    function(fileContents, next){
      var stocksJson = JSON.parse(fileContents);
      if (stocksJson[ticker]) {
        console.log(ticker+' price : ' + stocksJson[ticker].price);
        console.log('changing the value...');
        stocksJson[ticker].price = value;
        console.log('Price after the change has been made -- ' + stocksJson[ticker].price);
        console.log('printing the the Json.stringify');
        console.log(JSON.stringify(stocksJson, null, 4));
        var stocks_json_string = JSON.stringify(stocksJson, null, 4);
        fs.writeFile('stocktest.json',stocks_json_string, next);
      }else{
        next('nothing to write ' + ticker + ' was null');
      }
    }
  ], cb);
}


var q = async.queue(function (stockdata, callback) {
    updateJson(stockdata.ticker, stockdata.price, function(err, result){
      if(err){
        console.log(err);
      }
      // success
      callback();
    });
    
}, 1);


// assign a callback
q.drain = function() {
    console.log('all items have been processed');
}

q.push([{ticker: 'AAPL', price: '1000.33'},{ticker: 'BLAH', price: '111.22'}], function (err) {
    console.log('finished processing ticker item');
});