bahmutov

// I am trying to open PouchDB normally, but this fails in Firefox Incognito mode
var db = new PouchDB('test');
// InvalidStateError
// I see the idb error callback being called if the open request fails
exports.idbError = function (callback) {
  return function (event) {
    var message = (event.target && event.target.error &&
      event.target.error.name) || event.target;
    callback(errors.error(errors.IDB_ERROR, message, event.type));
  };

bahmutov

// NOTE does not work in strict mode
function parent(a, b) {
  console.log('in parent, a', a, 'b', b);
  var parentArguments = arguments;

  function child() {
    console.log('in child, a', a, 'b', b);
    console.log('is parentArguments === c.args?', parentArguments === c.args);
    console.log('parentArguments', parentArguments);
    return a + b;

bahmutov

Setting up Git message validation hook

Install pre-git for handling Git hooks and commitizen for helping format the commit messages

npm install pre-git commitizen cz-conventional-changelog --save-dev

bahmutov

// node-canvas
var Canvas = require('canvas')
console.log('Canvas is', Canvas)
var nodeCanvas = new Canvas(120, 120)
var ctx = nodeCanvas.getContext('2d')

// canvas-5-polyfill patches CanvasRenderingContext2D.prototype
// lets give it one
global.CanvasRenderingContext2D = {};
global.CanvasRenderingContext2D.prototype = ctx;

bahmutov

# See list of docker virtual machines on the local box
$ docker-machine ls
NAME      ACTIVE   URL          STATE     URL                         SWARM   DOCKER   ERRORS
default   *        virtualbox   Running   tcp://192.168.99.100:2376           v1.9.1 

# Note the host URL 192.168.99.100 - it will be used later!

# Build an image from current folder under given image name
$ docker build -t gleb/demo-app .

bahmutov

Goal: try redis inside a Docker container

Run Redis Docker image

1. Open docker terminal

• displays docker is configured to use the default machine with IP 192.168.99.100

2. Start redis:alpine prebuilt container from docker hub.

• docker run --name redis -p 6379:6379 -d redis:alpine
• the "alpine" image is very slim (5MB!)
• the running container binds the internal port 6379 to the "outside" world port with same number

bahmutov

On Mac OSX

To find the local network (WIFI usually) address ipconfig getifaddr en0

ipconfig getifaddr en0

192.168.0.8

bahmutov

Goal: run a simple NodeJS application inside a Docker container

Subgoal: give it access to local files.

docker run -it --rm --name example -v "$PWD":/usr/src/app -w /usr/src/app node:5-slim node index.js

output:

bahmutov

// A: is this pure function?
function sum(a, b) { return a + b }
// B: is this a pure function?
const k = 2
function addK(a) { return a + k }
// C: is this a pure function?
function sub(a, b) { return sum(a, -b) }
// D: is this a pure function?
function sub(a, b, summer) { return summer(a, b) }
// E: is this a pure function?

bahmutov

// if our data is more complicated and has to form things from items for example
// just pass around list of functions
const API = {
  github: (username) => 'http://github.com/' + username,
  photo: (username) => `http://github.com/${username}/avatar/`
}
const users = ['bahmutov', 'adity']
Object.keys(API).forEach((apiName) => {
  const formApiUrl = API[apiName]
  describe('api ' + apiName, () => {