StackGenVis/frontend/node_modules/now-and-later/lib/mapSeries.js

'use strict';

var once = require('once');

var helpers = require('./helpers');

function mapSeries(values, iterator, extensions, done){
  // allow for extensions to not be specified
  if(typeof extensions === 'function'){
    done = extensions;
    extensions = {};
  }

  // handle no callback case
  if(typeof done !== 'function'){
    done = helpers.noop;
  }

  done = once(done);

  // will throw if non-object
  var keys = Object.keys(values);
  var length = keys.length;
  var idx = 0;
  // return the same type as passed in
  var results = helpers.initializeResults(values);

  var exts = helpers.defaultExtensions(extensions);

  var key = keys[idx];
  next(key);

  function next(key){
    var value = values[key];

    var storage = exts.create(value, key) || {};

    exts.before(storage);
    iterator(value, once(handler));

    function handler(err, result){
      if(err){
        exts.error(err, storage);
        return done(err, results);
      }

      exts.after(result, storage);
      results[key] = result;

      if(++idx >= length){
        done(err, results);
      } else {
        next(keys[idx]);
      }
    }
  }
}

module.exports = mapSeries;