Maya Shavin

Smart & Controllable UI

with

Maya Shavin

State management

MobX

manage state flow of different user interface controls

State management

Set local state

Update local state

Render component

Multiple clicks?

Loading state?

Error state?

Disabled?

Bottom 🆙

Basic actions

New action

New action

Bug fixes

Bug fixes

Bottom 🆙

Difficult to maintain

Difficult to test

🐛

Hard to understand

State Machines

Finite

Deterministic Finite Automata

Deterministic

Finite

Automaton

one initial state

finite number of states

finite number of events

transition map triggered by events

Promises

Async/Await

Callbacks

Observables

UI phases/components are dependent

Transition between phases based on actions

Actions are events triggered

Building user interfaces === building user           

diagrams

graphs

trees

flows

State machines & state charts for modern web

Create

Interpret

Execute

State machine/chart

Manage

State machine/chart

Machine
transition
Events

State machine/chart

Actions
States
const fetchMachine = Machine({
    id: 'fetch',
    initial: 'idle',
    context: { retries: 0 },
    states: {
      idle: {
        on: {
          FETCH: 'loading'
        }
      },
      loading: {
        on: {
          RESOLVE: 'success',
          REJECT: 'failure'
        }
      },
      success: {
        type: 'final'
      },
      failure: {
        on: {
          RETRY: {
            target: 'loading',
            actions: assign({
              retries: (context, event) => context.retries + 1
            })
          }
        }
      }
    }
  });

inactive

toggle

active

toggle

import { Machine } from 'xstate';

export const toggleMachine = Machine({
  id: 'toggle',
  context: {
    /* some data */
  },
  initial: 'inactive',
  states: {
    inactive: {
      on: { toggle: 'active' }
    },
    active: {
      on: { toggle: 'inactive' }
    }
  }
});

Advantages of XState

Code reusability

Test coverage

Code scalability & maintenance 

Better code design & planning

Easy to debug and spot bugs

Visually clear view of the code flow

Resources

State machine/chart

console.log(Maya)

Senior Software Engineer

Core maintainer of StorefrontUI

NuxtJS Ambassador

Everything about Frontend/Web

Media Developer Expert (MDE)

THANK YOU!

Plan. Model. Develop

Smart & Controllable UI with (X)state machine

By Maya Shavin

Smart & Controllable UI with (X)state machine

UI components are built on user flows or state graphs. To manage these states, we usually resolved to boolean variables system like isLoading. But this proves to be buggy and hard to maintain as the codebase grows. There is a better solution. In my talk, we will explore how to fully control our app's states and develop a more adaptive UI system to users' behavior with state machines, statecharts and more.

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