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: 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

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

// following along https://medium.com/@luijar/kliesli-compositions-in-javascript-7e1a7218f0c4
const R = require('ramda')
const Maybe = require('ramda-fantasy').Maybe

// parse JSON string into object
// parse :: String -> Object | Null
function parse(s) {
  try {
    return JSON.parse(s)
  } catch (e) {

bahmutov

it('until the number 7 appears', () => {
    const checkAndReload = () => {
      // get the element's text, convert into a number
      cy.get('#result').should('not.be.empty')
      .invoke('text').then(parseInt)
      .then((number) => {
        // if the expected number is found
        // stop adding any more commands
        if (number === 7) {
          cy.log('lucky **7**')

bahmutov

```js
/// <reference types="Cypress" />
describe('intercept', () => {
  it('stubs anchor ping', () => {
    cy.visit('/')
    cy.intercept({
      method: 'POST',
      pathname: '/track'
    }, {}).as('ping')
    cy.get('a[ping]').click()

bahmutov

Keybase proof

I hereby claim:

• I am bahmutov on github.
• I am glebb (https://keybase.io/glebb) on keybase.
• I have a public key ASBM0WBon-OfVjLsNOuqvrPMbR0HNkjc9zdg42Sxp-K3kQo

To claim this, I am signing this object:

bahmutov

Gleb Bahmutov is JavaScript ninja, image processing expert and software quality fanatic. After receiving a PhD in computer science from Purdue University, Gleb worked on laser scanners, 3D reconstruction, and panorama-based virtual tours at EveryScape. Later Gleb switched to writing browser data visualization software at MathWorks. After a year, Gleb went back to the startup environment and developed software quality analysis tools at uTest (now Applause). Today Gleb is developing real-time financial analysis tools at Kensho. He blogs about software development topics at http://bahmutov.calepin.co/ and links his projects at http://glebbahmutov.com/. You can follow him and his work @bahmutov

bahmutov

Printing wallclock timestamps and frame timestamps (since common start)

cypress:server:video 1.3989999294281006 frame 1.326711893081665 received screencastFrame +0ms
  cypress:server:video 1.5299999713897705 frame 1.4792709350585938 received screencastFrame +131ms
  cypress:server:video 2.922999858856201 frame 2.340052843093872 received screencastFrame +1s
Browserslist: caniuse-lite is outdated. Please run next command `npm update caniuse-lite browserslist`
  cypress:server:video 4.042999982833862 frame 2.4192519187927246 received screencastFrame +1s
  cypress:server:video 4.049000024795532 frame 2.584810972213745 received screencastFrame +7ms

bahmutov

Imagine I want to separate caching for offline support from other features. I would load first service worker to cache index.html and static resources in /static and would load second service worker to do other things.

<script>
    if ('serviceWorker' in navigator) {
      console.log('page is registering two service workers')
      // one.js should cache index.html and /static folder
 navigator.serviceWorker.register('one.js', {scope: './'})