remove_reaction() — svelte Function Reference

Source Code

packages/svelte/src/internal/client/runtime.js lines 362–403

function remove_reaction(signal, dependency) {
	let reactions = dependency.reactions;
	if (reactions !== null) {
		var index = index_of.call(reactions, signal);
		if (index !== -1) {
			var new_length = reactions.length - 1;
			if (new_length === 0) {
				reactions = dependency.reactions = null;
			} else {
				// Swap with last element and then remove.
				reactions[index] = reactions[new_length];
				reactions.pop();
			}
		}
	}

	// If the derived has no reactions, then we can disconnect it from the graph,
	// allowing it to either reconnect in the future, or be GC'd by the VM.
	if (
		reactions === null &&
		(dependency.f & DERIVED) !== 0 &&
		// Destroying a child effect while updating a parent effect can cause a dependency to appear
		// to be unused, when in fact it is used by the currently-updating parent. Checking `new_deps`
		// allows us to skip the expensive work of disconnecting and immediately reconnecting it
		(new_deps === null || !includes.call(new_deps, dependency))
	) {
		var derived = /** @type {Derived} */ (dependency);

		// If we are working with a derived that is owned by an effect, then mark it as being
		// disconnected and remove the mark flag, as it cannot be reliably removed otherwise
		if ((derived.f & CONNECTED) !== 0) {
			derived.f ^= CONNECTED;
			derived.f &= ~WAS_MARKED;
		}

		update_derived_status(derived);

		// Disconnect any reactions owned by this reaction
		destroy_derived_effects(derived);
		remove_reactions(derived, 0);
	}
}