Asynchronous programming and continuation-passing style in JavaScript

E篇文主要講Continuation passing style (CPS)。

• 由synchronus function 係javascript改寫成 asynchronus function，其實姐係改寫成 CPS
• 理解左CPS，就可以人手寫一D async function去處理loop，recursion，同tree iteration
• 將E個技巧generize，就係Promise嘅implementation。
• Generator 係另一種async programming嘅寫法，其實背後都係用CPS implement出黎
• CPS 將nested嘅function拆開左做chain pattern，其實係一種inversion of control，令到D logic 好maintain左
• CPS similar to function implement with goto, does not use stack to hold variable
• All true CPS function calls are tail calls and can be optimized
  • As we mentioned that CPS does not use stack
• Trampolining，姐係一種對tail recursion，以array 做 implementation嘅handling
  • 條array其實係一條queue
• Browser 用event queue去處理trampolining，成個CPS嘅overview就係js async programming model

Crafting beautiful UX with API requests

Handling API call in web app, to provide better UX to user

• Timeouts
  • Cancel my request if you’re slower to respond than I want
  • Shouldn’t let user wait too long
  • Use API client timeout config, instead of writing your own
• Minimum wait time
  • Protect your app from fast API response
  • If you have a loading state, and don’t want the data pop up suddenly
  • Don’t use when user expect a very fast response
    • Avoid unnecessory wait time
• Retry
  • As an hotfix of some infrastructure problem
  • Use exponential backoff, increase the retry interval exponentially

17 Jan 2019

Can read the implementation

Eagles Don’t Fly With Turkeys

• Manager prefer not to deal with underperformer in the team
  • They believe that having someone in the position is better than an empty seat
  • They know that hiring is a lot of work and they don’t want to do it
  • They hope things will get better magically
• This will demoralize high performaning member
• B-players hire C-players because they want to make themselves look good
  • The team will fill with lower-performing team member soon

12 common mistakes made when using Story Points

• Story point is a rough indication of how much time an item will take to complete
• Benefits
  • Quick estimation
  • Estimation without giving a specific time commitment
  • Embrace uncertainty that comes with estimation
• Common mistakes
  1. Equating Story Points to just complexity, uncertainty or value
     • Story points are about effort, we can take complexity and uncertainty into consideration
     • Story is not simply equal to complexity or risk
  2. Translate story points to hours
  3. Averaging the story point
     • If half of the team give 3 points and the other half give 5, pick either 3 or 5 story point to the item
  4. Adjusting Story Point estimates of issues during sprint.
     • Change the story point lose the information of inaccurate estimation
     • Keep inaccurate estimation as part of the historical velocity of a team
  5. Story pointing bugs, unless the bug is unrelated to the current sprint
     • Bugs of feature to be implemented in this sprint is part of the feature story, we should not consider it is an extra task
  6. Adding Story Points to small tasks
     • We should timebox the small task
     • Tasks required a fixed amount of time to complete do not need story point
  7. Adjusting reference of one story point
     • Velocity of different sprints is no longer comperable
  8. Story pointing unfinished issues again
  9. Adjusting Story Point estimate because a specific developer will work on it
     • The same task will be assign to different people in some situation
       • e.g senior engineer fixing emergency bugs, junior engineer need to pick up the tasks
  10. Never adjusting story point’s reference
      • We should tune the reference when the team become mature
      • or new junior members join the team
  11. Conforming to the expert in the room
      • Let the rest of the team estimate without the expert
  12. Not discussing incorrectly Story-Pointed issues in retrospective
      • We need to improve our estimation

History through the eyes of a chicken

• Chicken orgin from India
• Chicken is cross breed of 4 species
• Chicken lay egg daily

Intro to Chaos Engineering

• Chaos Engineering is to break things in purpose
  • Don’t do it in production
• Call leader
  • Responsible for any type of incidents
  • Requirements:
    • Good understanding on all services
    • Know who are the different people that own the services
    • Incident downstream and upstream impact
    • Know who are the people you need to get online to fix the issue
• Which system to start chaos engineering
  • Critical service
    • System serve critical function or store critical data
  • Because
    • Better monitory and recovery tool set up already
    • Better knowledge on the system
    • Huge team which works on the system
• Prerequisities for Chaso Engineering
  • High Severity Incident (SEV) Management including SEV levels and definitions
  • Availability monitoring, including a high level health dashboard for WWW and API
  • Alerts and paging that call a human and wake them up for SEVs
• Random error injection help less
  • It cannot provide much information
  • Don’t do it unless you are very confident on the recovery systems
• Give names to severe incidents
  • Easier to refer SEV back to the name
  • Easier to remember the SEV

以下無需重讀

AARRR 指標能評判設計成效？UX 更需要的是分析使用者的行為數據 (上) (下)

• AARRR 比較適用電商和內容網站，唔太適合有功能嘅產品
  • AARRR嘅數據係睇有幾多個user用，有幾多個user肯俾錢，唔可以直接了解到user嘅行為
  • 用AARRR去tune UX，好可能俾D細節騎劫左，最重要嘅使用者特性、行為同內在需求係冇調查到
• 直接測量關鍵行為的數據會好D
• 睇行為事件間的流量轉移
  • 如果user嘅行動流程同我地預計嘅唔同，表示我地要重新認識user
  • 透過觀察而去揾出insight

Behavior-Driven Development (BDD) Crash Course

• BDD steps
  • Writing feature doc with customer
  • Everyone agree with the feature
  • Automated test will be generated from feature doc
    • It becomes TDD after test is generated
• 3 section of a feature doc
  • Context
  • Event
  • Outcome
• Having a clear definition on expected behaviour, can avoid overkill
• BDD test is slower than unit test
  • It is integration test or end to end test
• BDD cannot help you locate the root of cause
  • Use unit test if you want it

Increase your self-awareness with one simple fix

• People who introspected were more stressed and depressed, less satisfied with their jobs and their relationships, less in control of their lives
• Thinking about ourselves isn’t related to knowing ourselves
• Don’t ask “Why”, ask “What”
  • Human cannot remove their unconscious thoughts, feelings and motives
    • We end up inventing answers that feel true but are often very wrong
  • Our feeling and thought easily affect by the event happened recently
    • We cannot answer “Why” rationally
    • Answer of “Why” leads us away from our true nature
• Think about what you can do

速讀的殘酷真相

學野係要吸收要思考，好多位係快唔到。
速讀可以用係資訊含量低嘅文章到，高質嘅書始終要慢讀。
比起睇得快，㨂高質嘅書睇係更重要

Why do Americans and Canadians celebrate Labor Day?

七月到十一月冇假，所以係九月放一日勞動節假。之後爆發一次嚴重嘅勞工運動，做成多人死亡。五月一日嘅國際勞動節就係記念E件事。