Part 1 / Reactivity / Assignments

At the heart of Svelte is a powerful system of reactivity for keeping the DOM in sync with your application state — for example, in response to an event.

To demonstrate it, we first need to wire up an event handler (we'll learn more about these later):

<button on:click={increment}>

Inside the increment function, all we need to do is change the value of count:

function increment() {
	count += 1;
}

Svelte 'instruments' this assignment with some code that tells it the DOM will need to be updated.