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// find all duplicate ids
function show_elements_with_duplicate_ids(){
	const duplicate_ids = new Set();
	const ids_found = new Set();
	const elems_with_ids = Array.from(document.querySelectorAll('*[id]'));
	elems_with_ids.forEach(elem => {
		if(ids_found.has(elem.id)){
			duplicate_ids.add(elem.id);
		}
		else{
			ids_found.add(elem.id);
		}
	});
	const elems_with_duplicate_ids = elems_with_ids.filter(elem => duplicate_ids.has(elem.id));
	console.log(elems_with_duplicate_ids);
}
show_elements_with_duplicate_ids();





// find all imgs without alts
document.querySelectorAll('img:not([alt])');