André Kovac
Aug 22, 2022
What the heck do "declarative" and "reactive" actually mean?
#1about 2 minutes
Understanding imperative vs declarative with an analogy
An analogy of tidying a room illustrates the difference between giving step-by-step instructions (imperative) and describing the desired final state (declarative).
#2about 7 minutes
The challenge of manual DOM manipulation in JavaScript
A vanilla JavaScript counter example demonstrates the imperative process of manually querying and updating the DOM to synchronize application state with the UI.
#3about 3 minutes
How the browser renders HTML, CSS, and JavaScript
An overview of the browser's rendering pipeline shows how it converts HTML and CSS into a DOM and CSSOM to paint pixels on the screen.
#4about 4 minutes
Introducing the core concepts of reactive programming
Reactive programming is introduced using a spreadsheet analogy, where changing one value automatically updates all dependent values, aiming for a UI that is a function of its state.
#5about 5 minutes
Abstracting DOM updates with a custom state object
A simple state object with a `setValue` method is created to encapsulate imperative DOM manipulation, making the event handler more declarative.
#6about 4 minutes
The imperative pitfalls of conditional UI rendering
Attempting to conditionally add an element to the DOM imperatively reveals common bugs and makes the UI difficult to reason about from the code.
#7about 3 minutes
How React enables declarative UI with a virtual DOM
React's declarative approach is demonstrated, using a virtual DOM and the `useState` hook to describe the UI's appearance based on state.
#8about 2 minutes
Svelte's approach to truly reactive state updates
Svelte simplifies reactivity by making standard JavaScript assignments automatically trigger UI updates, removing the need for setter functions.
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