Function hydrate

packages/svelte/src/internal/client/render.js:95–151

(component, options)

 * @returns {Exports}
 */
export function hydrate(component, options) {
	init_operations();
	options.intro = options.intro ?? false;
	const target = options.target;
	const was_hydrating = hydrating;
	const previous_hydrate_node = hydrate_node;

	try {
		var anchor = get_first_child(target);

		while (
			anchor &&
			(anchor.nodeType !== COMMENT_NODE || /** @type {Comment} */ (anchor).data !== HYDRATION_START)
		) {
			anchor = get_next_sibling(anchor);
		}

		if (!anchor) {
			throw HYDRATION_ERROR;
		}

		set_hydrating(true);
		set_hydrate_node(/** @type {Comment} */ (anchor));

		const instance = _mount(component, { ...options, anchor });

		set_hydrating(false);

		return /**  @type {Exports} */ (instance);
	} catch (error) {
		// re-throw Svelte errors - they are certainly not related to hydration
		if (
			error instanceof Error &&
			error.message.split('\n').some((line) => line.startsWith('https://svelte.dev/e/'))
		) {
			throw error;
		}
		if (error !== HYDRATION_ERROR) {
			// eslint-disable-next-line no-console
			console.warn('Failed to hydrate: ', error);
		}

		if (options.recover === false) {
			e.hydration_failed();
		}

		// If an error occurred above, the operations might not yet have been initialised.
		init_operations();
		clear_text_content(target);

		set_hydrating(false);
		return mount(component, options);
	} finally {
		set_hydrating(was_hydrating);
		set_hydrate_node(previous_hydrate_node);
	}
}