How to remove data-* attributes using HTML5 dataset

A rather simpler and straightforward approach:

const someElement = document.querySelector('...');

Object.keys(someElement.dataset).forEach(dataKey => {
  delete someElement.dataset[dataKey];
});

Wouldn't 'delete' remove dataset element? E.g.:

<div id="a1" data-foo="bar">test</div>

<script>
var v = document.getElementById('a1');  
alert(v.dataset.foo);
delete v.dataset.foo;
alert(v.dataset.foo);
</script>