Function init

packages/svelte/src/internal/client/dom/legacy/lifecycle.js:12–68

(immutable = false)

 * @param {boolean} [immutable]
 */
export function init(immutable = false) {
	const context = /** @type {ComponentContextLegacy} */ (component_context);

	const callbacks = context.l.u;
	if (!callbacks) return;

	let props = () => deep_read_state(context.s);

	if (immutable) {
		let version = 0;
		let prev = /** @type {Record<string, any>} */ ({});

		// In legacy immutable mode, before/afterUpdate only fire if the object identity of a prop changes
		const d = derived(() => {
			let changed = false;
			const props = context.s;
			for (const key in props) {
				if (props[key] !== prev[key]) {
					prev[key] = props[key];
					changed = true;
				}
			}
			if (changed) version++;
			return version;
		});

		props = () => get(d);
	}

	// beforeUpdate
	if (callbacks.b.length) {
		user_pre_effect(() => {
			observe_all(context, props);
			run_all(callbacks.b);
		});
	}

	// onMount (must run before afterUpdate)
	user_effect(() => {
		const fns = untrack(() => callbacks.m.map(run));
		return () => {
			for (const fn of fns) {
				if (typeof fn === 'function') {
					fn();
				}
			}
		};
	});

	// afterUpdate
	if (callbacks.a.length) {
		user_effect(() => {
			observe_all(context, props);
			run_all(callbacks.a);
		});
	}
}