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World Congress 2022 • Aug 22, 2022

What the heck do "declarative" and "reactive" actually mean?

André Kovac

Are you still writing brittle, imperative DOM updates? Discover what declarative and reactive programming actually mean for modern frontend development.

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#1 about 3 min

Understanding the difference between declarative and imperative programming

Real-world analogies demonstrate the difference between explaining exact steps and describing the desired outcome.

#2 about 7 min

Manipulating the browser DOM with vanilla JavaScript

Interacting directly with the document object model creates brittle workflows when exposing state variables.

#3 about 4 min

Synchronizing application state with user interface rendering

Managing updates between JavaScript variables and the visual render tree manually causes state mismatch bugs.

#4 about 4 min

Understanding the core concepts of reactive programming

Establishing automated synchronization bonds between variables eliminates the need for manual value reassignment over time.

#5 about 4 min

Abstracting manual DOM changes with state setter functions

Treating the user interface as a direct outcome of state limits explicit document queries within event handlers.

#6 about 6 min

Handling derived state and conditional rendering imperatively

Dynamically creating and inserting elements based on changing conditions leads to unreadable imperative commands.

#7 about 4 min

Building declarative user interfaces using React and virtual DOM

Utilizing an in-memory representation allows component logic to dictate layout directly without manual document manipulation steps.

#8 about 3 min

Achieving true reactivity through variable assignments in Svelte

Compiler-driven approaches bypass explicit setter methods by transforming standard variable assignments directly into real-time visual updates.

Matching moments

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Comparing imperative and declarative UI development paradigms

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Establishing a practical definition of reactivity

Michał Moroz Michał Moroz · WWC 2024

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Introduction to react components, props, and state

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