Function reconcile

packages/svelte/src/internal/client/dom/blocks/each.js:428–654

* Add, remove, or reorder items output by an each block as its input changes * @template V * @param {EachState} state * @param {Array<V>} array * @param {Element | Comment | Text} anchor * @param {number} flags * @param {(value: V, index: number) => any} get_key * @returns {void}

(state, array, anchor, flags, get_key)

 * @returns {void}
 */
function reconcile(state, array, anchor, flags, get_key) {
	var is_animated = (flags & EACH_IS_ANIMATED) !== 0;

	var length = array.length;
	var items = state.items;
	var current = skip_to_branch(state.effect.first);

	/** @type {undefined | Set<Effect>} */
	var seen;

	/** @type {Effect | null} */
	var prev = null;

	/** @type {undefined | Set<Effect>} */
	var to_animate;

	/** @type {Effect[]} */
	var matched = [];

	/** @type {Effect[]} */
	var stashed = [];

	/** @type {V} */
	var value;

	/** @type {any} */
	var key;

	/** @type {Effect | undefined} */
	var effect;

	/** @type {number} */
	var i;

	if (is_animated) {
		for (i = 0; i < length; i += 1) {
			value = array[i];
			key = get_key(value, i);
			effect = /** @type {EachItem} */ (items.get(key)).e;

			// offscreen == coming in now, no animation in that case,
			// else this would happen https://github.com/sveltejs/svelte/issues/17181
			if ((effect.f & EFFECT_OFFSCREEN) === 0) {
				effect.nodes?.a?.measure();
				(to_animate ??= new Set()).add(effect);
			}
		}
	}

	for (i = 0; i < length; i += 1) {
		value = array[i];
		key = get_key(value, i);

		effect = /** @type {EachItem} */ (items.get(key)).e;

		if (state.outrogroups !== null) {
			for (const group of state.outrogroups) {
				group.pending.delete(effect);