As an added bonus, I just create 3.0.0 which reduced the size from 10kb to 3kb :)

Since html-element does not use data-set for reading 'data-*' attributes this breaks serializing of 'data-*' attributes.

Either the data-set module needs fixing or html-document can use data-set for reading data.

what changed in dataset? does it store objects as JSON now or something like that?
how would they get the data out if they didn't use your module? show me the code.

@dominictarr so data-set always weakly attached data on the dom element if native elem.dataset was not supported.

This means currently in IE<11 to access data you put in hyperscript elements you would have to use DataSet(elem).key

Now due to elem.dataset converting values into strings, I've removed the native usage and always use the weak attaching of data approach.

Which means to read data-* properties out of dom elements you would have to do:

var h = require('hyperscript')
var DataSet = require('data-set')
var assert = require('assert')

var elem = h('div', {
  'data-foo': { bar: 'baz' }
});
var ds = DataSet(elem)
assert.deepEqual(ds.foo, { bar: 'baz' })

Previously if you accessed elem.dataset.foo or elem.getAttribute('data-foo') your code would have failed in IE<11. i.e. not accessing 'data-' attributes through the data-set module is a leaky cross browser abstraction.

A valid alternative to this PR is to completely remove the dependency on data-set and do elem.setAttribute(key, value).

oh... so are you saying that although data-set started as a polyfill for data- attributes, you have removed that completely and now it's not using that at all?

@dominictarr it started off as a polyfill for data- attributes that was

function DataSet(elem) {
  return elem.dataset ? dataset : polyfill(elem)
}

Now it's

function DataSet(elem) {
  return polyfill(elem)
}

The polyfill always weakly attached the dataset to the element.

The important back compat breaking change is ( npm-dom/data-set@3f0ec1a )

right - so it's not a polyfil anymore! it's just a weakmap! but it looks like it's it's a polyfil.
I think this would be quite surprising to users of this module.
This is a module for generating html, so sticking to the standards makes sense, and strapping on new features (like weakmaps) doesn't.

Is there another way you can use weakmaps like you are without me merging this?

@dominictarr thinking about it more I think I should close this and you should remove data-set completely and call elem.setAttribute('data-foo', value).