djia

Get the opening Dow Jones Industrial Average for a date, or the most recent opening if the market is closed for that day.

It fetches data from a web service, with the option to cache the results for future requests.

I use this for xkcd Geohashing.

Install

npm install djia

Usage

import djia from 'djia'

djia('2015-03-27', (err, value) => {
    // err: null
    // value: 17673.63
})

djia('1900-01-01', (err) => {
    // err: [Error: date too much in the past]
})

djia('2999-01-01', (err) => {
    // err: [Error: data not available yet]
})

// Cache the result in $HOME/.config/djia
djia({date: '2015-03-27' cache: true}, (err, value) => {})

// Cache it in your current directory
djia({date: '2015-03-27' cache: process.cwd()}, (err, value) => {})

API

djia(options, callback)

options (YYYY-MM-DD formatted date string or object)

The first paramter is either a YYYY-MM-DD date string or an object of options.

options.date (required, YYYY-MM-DD formatted date string)

If you are using the object form, then pass in the formatted date string using the date key.

options.cache (optional, can be true or path to cache directory/file in node or cache prefix in the browser)

Since the fetched data will never change (it is only for the opening value), it can make sense to cache it. There are slight differences in how this works if you are using it in the browser vs Node.

Node If you pass in true then a cache directory will be created for you at $HOME/.config/djia. You can also pass in a path to your own cache directory or a .json file, and they will be created if they do not exist. If your path ends in .json thats where the cache will be, otherwise it is assumed you are passing in a direcotry and the path will be DIRECTORY/djia_cache.json.

Browser It will use localforage to cache everything. If you pass in true then each key will be prefixed with djia_, otherwise pass in a string and it will use that. The key format is PREFIX_DATE.

callback(err, value)

err will be an Error object with a message most likely from the web service. value will be the Dow Jones opening value as a number.

Contributing

This is written in ES6 and compiled to ES5 using babel. The code you require will come from the lib/ directory which gets compiled from src/ before each npm publish.

Tests

npm test

License

MIT