Call initFunc on elements in selector that are in DOM now and also on dynamically-added elements later on

dynamicInit.js

// Call initFunc on elements in selector that are in DOM now and also on dynamically-added elements later on
function dynamicInit(selector, initFunc) {
    //console.log('dynamicInit', selector)
    window._dynamicInitData ??= [];
    window._dynamicInitData.push({ selector, initFunc });

    if (!window._dynamicInitObserver) {
        window._dynamicInitObserver = new MutationObserver(function (mutations) {
            // avoid infinite loop when we add new elements below
            window._dynamicInitObserver.disconnect()
            for (let mutation of mutations) {
                for (let addedNode of mutation.addedNodes) {
                    if (addedNode.nodeName != '#text' && addedNode.nodeName != '#comment') {
                        //console.log(' ... dynamicInit', addedNode)

                        window._dynamicInitData.forEach(function (item) {
                            //console.log('   ... dynamicInit', item.selector)

                            // short-circuit if selector not found
                            if (!addedNode.querySelector(item.selector))
                                return;

                            addedNode.querySelectorAll(item.selector).forEach(function (el) {
                                //console.log('   ... dynamicInit', item.selector, el)
                                if (!el.dataset['dynamicinit']) {
                                    //console.log('dynamically init-ing', item.selector, el)
                                    item.initFunc.apply(el)
                                }
                                el.dataset['dynamicinit'] = 1
                            })

                        });
                    }
                }
            }
            // re-observe
            window._dynamicInitObserver.observe(document, { childList: true, subtree: true })
        })

        // start observing
        window._dynamicInitObserver.observe(document, { childList: true, subtree: true })
    }

    // initial init
    document.querySelectorAll(selector).forEach(function (el) {
        if (!el.dataset['dynamicinit'])
            initFunc.apply(el)
        el.dataset['dynamicinit'] = 1
    })
}