Function constructNewChildrenArray

src/diff/children.js:155–338

* @param {VNode} newParentVNode * @param {ComponentChildren[]} renderResult * @param {VNode[]} oldChildren

(
	newParentVNode,
	renderResult,
	oldChildren,
	oldDom,
	newChildrenLength
)

 * @param {VNode[]} oldChildren
 */
function constructNewChildrenArray(
	newParentVNode,
	renderResult,
	oldChildren,
	oldDom,
	newChildrenLength
) {
	/** @type {number} */
	let i;
	/** @type {VNode} */
	let childVNode;
	/** @type {VNode} */
	let oldVNode;

	let oldChildrenLength = oldChildren.length,
		remainingOldChildren = oldChildrenLength;

	let skew = 0;

	newParentVNode._children = new Array(newChildrenLength);
	for (i = 0; i < newChildrenLength; i++) {
		// @ts-expect-error We are reusing the childVNode variable to hold both the
		// pre and post normalized childVNode
		childVNode = renderResult[i];

		if (
			childVNode == NULL ||
			typeof childVNode == 'boolean' ||
			typeof childVNode == 'function'
		) {
			newParentVNode._children[i] = NULL;
			continue;
		}
		// If this newVNode is being reused (e.g. <div>{reuse}{reuse}</div>) in the same diff,
		// or we are rendering a component (e.g. setState) copy the oldVNodes so it can have
		// it's own DOM & etc. pointers
		else if (
			typeof childVNode == 'string' ||
			typeof childVNode == 'number' ||
			// eslint-disable-next-line valid-typeof
			typeof childVNode == 'bigint' ||
			childVNode.constructor == String
		) {
			childVNode = newParentVNode._children[i] = createVNode(
				NULL,
				childVNode,
				NULL,
				NULL,
				NULL
			);
		} else if (isArray(childVNode)) {
			childVNode = newParentVNode._children[i] = createVNode(
				Fragment,
				{ children: childVNode },
				NULL,
				NULL,
				NULL
			);