Question

According to the dataset specification, how is element.dataset meant to delete data attributes? Consider:

<p id="example" data-a="string a" data-b="string b"></p>

If you do this:

var elem = document.querySelector('#example');
elem.dataset.a = null;
elem.dataset.b = undefined;
elem.dataset.c = false;
elem.dataset.d = 3;
elem.dataset.e = [1, 2, 3];
elem.dataset.f = {prop: 'value'};
elem.dataset.g = JSON.stringify({prop: 'value'});

the DOM becomes this in Chrome and Firefox:

<p id="example" 
   data-a="null" 
   data-b="undefined" 
   data-c="false" 
   data-d="3" 
   data-e="1,2,3" 
   data.f="[object Object]" 
   data.g="{"prop":"value"}"
></p>

The Chrome/Firefox implementations mimic setAttribute. It basically applies .toString() first. This makes sense to me except for the treatment of null because I would expect that null would remove the attribute. Otherwise how does the dataset API do the equivalent of:

elem.removeAttribute('data-a');

And what about boolean attributes:

<p data-something> is equivalent to <p data-something=""> Hmm.

Answer 1

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>