Javascript Event Issue

let handleTraitFilter = (e) => {
	return new Promise((resolve, reject) => {
		let categoryLink = e.currentTarget,
			filterValue = categoryLink.getAttribute('data-filter'),
			isActive = toggleActive(categoryLink);
		if (isActive === true) {
			addFilterString(filterValue)
		} else {
			removeFilterString(filterValue);
		}
		if (getFilterClass()) {
			filterItems();
		} else {
			showAll();
		}
		setGalleryURL();
		iso.on('layoutComplete', () => {
			resolve();
		});
	});
};

let setLoader = (e) => {
	e.currentTarget.classList.add('loading');
	gallery.querySelector('.gallery-loader').style.display = 'flex';
	e.currentTarget.style.display = 'none';
	e.currentTarget.style.display = 'block';
};

let addListenerToElems = (elems, eventString, handler) => {
	let i = 0,
		count = elems.length;
	while (i < count) {
		elems[i].addEventListener(eventString, handler);
		i++;
	}
}

addListenerToElems(document.querySelectorAll('.traits-list a'), 'mousedown', e => {
	setLoader(e);
	setTimeout(() => {
		console.log(e);
		handleTraitFilter(e).then(() => {
			removeClassFromElems(document.querySelectorAll('.loading'), 'loading')
			gallery.querySelector('.gallery-loader').style.display = 'none';
		});
	}, 10);
});