Add ES modules for modern bundlers

[greggb]

This is a fantastic library. The small size and single purpose were exactly what I was looking for.

I ran into a breaking bug when building for production with webpack 3, as uglify has trouble with mixed import and module.exports (expecting export default).

I rewrote the rollup config to use a newer syntax and added an ES module export. That export was also added to .gitignore and package.json under the module property so it can be resolved by webpack.

The tests all passed and the minified browser bundle does not return the export, just a function now.

[codecov]

Codecov Report

Merging #20 into master will increase coverage by <.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master      #20      +/-   ##
==========================================
+ Coverage    99.2%   99.21%   +<.01%     
==========================================
  Files           5        5              
  Lines         126      127       +1     
  Branches       29       29              
==========================================
+ Hits          125      126       +1     
  Misses          1        1

Impacted Files	Coverage Δ
src/browser.js	100% <ø> (ø)	⬆️

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[pveyes]

Nice!

I didn't experience any error when using webpack 3 but maybe because I haven't used some plugin like ModuleConcatenationPlugin

I'm assuming module field in package.json will only be used by webpack, and nodejs, so it's safe to build browser bundle

LGTM

[greggb]

Thanks! My hunch is it was the mangle settings I was using, but I wasn't able to narrow it down.

I'm assuming module field in package.json will only be used by webpack

That's my impression. Only module aware bundlers (and newer node) would make use of it.

For posterity here was the error I was getting when loading the page: Cannot set property 'exports' of undefined

and in webpack logs:

WARNING in <FILEPATH WHERE HTMR IS IMPORTED>
60:11-18 "export 'default' (imported as 'convert') was not found in 'htmr'

ERROR in <BUNDLE WHERE HTMR IS IMPORTED> from UglifyJs
Invalid assignment [./node_modules/htmr/lib/htmr.min.js:7,0] <BUNDLE WHERE HTMR IS IMPORTED> 
error Command failed with exit code 2.