Function watchForNodePosition

src/inject/utils/dom.ts:76–182

(
    node: T,
    mode: 'head' | 'prev-sibling',
    onRestore = Function.prototype,
)

}

export function watchForNodePosition<T extends Node>(
    node: T,
    mode: 'head' | 'prev-sibling',
    onRestore = Function.prototype,
): NodePosetionWatcher {
    const MAX_ATTEMPTS_COUNT = 10;
    const RETRY_TIMEOUT = getDuration({seconds: 2});
    const ATTEMPTS_INTERVAL = getDuration({seconds: 10});
    let prevSibling = node.previousSibling;
    let parent = node.parentNode;
    if (!parent) {
        throw new Error('Unable to watch for node position: parent element not found');
    }
    if (mode === 'prev-sibling' && !prevSibling) {
        throw new Error('Unable to watch for node position: there is no previous sibling');
    }
    let attempts = 0;
    let start: number | null = null;
    let timeoutId: ReturnType<typeof setTimeout> | null = null;
    const restore = throttle(() => {
        if (timeoutId) {
            return;
        }
        attempts++;
        const now = Date.now();
        if (start == null) {
            start = now;
        } else if (attempts >= MAX_ATTEMPTS_COUNT) {
            if (now - start < ATTEMPTS_INTERVAL) {
                logWarn(`Node position watcher paused: retry in ${RETRY_TIMEOUT}ms`, node, prevSibling);
                timeoutId = setTimeout(() => {
                    start = null;
                    attempts = 0;
                    timeoutId = null;
                    restore();
                }, RETRY_TIMEOUT);
                return;
            }
            start = now;
            attempts = 1;
        }

        if (mode === 'head') {
            if (prevSibling && prevSibling.parentNode !== parent) {
                logWarn('Sibling moved, moving node to the head end', node, prevSibling, parent);
                prevSibling = document.head.lastChild;
            }
        }

        if (mode === 'prev-sibling') {
            if (prevSibling!.parentNode == null) {
                logWarn('Unable to restore node position: sibling was removed', node, prevSibling, parent);
                stop();
                return;
            }
            if (prevSibling!.parentNode !== parent) {
                logWarn('Style was moved to another parent', node, prevSibling, parent);
                updateParent(prevSibling!.parentNode);