for-each-frame.js

function forEachFrame (fn, targetWindow = window, filter = () => null) {
    const frames = targetWindow.document.querySelectorAll('iframe, frame');

    for (const frame of frames) {
        if (filter(frame)) {
            continue;
        }

        try {
            fn(frame.contentWindow, frame);
        } catch (err) {
            console.warn('failed to access child frame', err.toString());
        }

        try {
            forEachFrame(fn, frame.contentWindow);
        } catch (err) {
            console.warn('failed to access nested child frame', err.toString());
        }
    }
}