Add standalone script compatibility

[josh-hemphill]

Add UMD (Universal Module) webpacked file for inclusion in plain js projects and automatic inclusion in UNPKG CDN

This would have the added benefit of being able to create codepens etc. for examples and testing.
I also added a basic example.html which includes the UMD and lets you test/experiment with it.

Note: No modification to index.js, just added webpack dev-dependency, npm run build command, example.html, and UMD directory/file (maybe eventually add beautified UMD expression-eval.js so CDN users can view source in codepens etc.)

[donmccurdy]

What is the engine requirement based on?

[josh-hemphill]

Webpack had some mention of it being sometimes necessary to specify. I think it was webpack's minimum supported version of node.
I just removed it since it's no longer necessary.

[donmccurdy]

Hi! Unfortunately I don't use Webpack regularly, and would prefer not to take on maintaining a build artifact that requires it. Would microbundle's unpkg output work for you? If so, I think this structure could be OK:

  "source": "index.js",                        // source file
  "main": "dist/expression-eval.js",           // output path for CommonJS/Node
  "module": "dist/expression-eval.module.js",  // output path for JS Modules
  "unpkg": "dist/expression-eval.umd.js",      // optional, for unpkg.com

It'd be fine to omit example.html as well, I'm willing to trust the test suite and microbundle's maintainers.

[josh-hemphill]

Yeah, microbundle works great, I didn't know it existed.
And I guess I went overboard with the example.html, since having a expression-eval.umd.js is supposed to allow making codepens etc. which would would fill that purpose.
I'll make a push shortly.

[josh-hemphill]

NPM is reporting that microbundle has several security vulnerabilities. So I added a notice not to use the standalone scripts in production at the moment.

[RobertoMaurizzi]

Shouldn't those vulnerabilities only affect the npm run build step, i.e they won't affect the generated code? Modules should be safe (and in addition the only High one involves svgo, an SVG optimizer)

[donmccurdy]

Right, the vulnerabilities are essentially false positives, and would only affect the person publishing the package to npm with devDependencies in any case (i.e. me). Let's remove the warning, otherwise this looks good. Thanks!

[donmccurdy]

Thanks!

[josh-hemphill]

@donmccurdy I apologize, I don't think I tested it. No matter how I try to direct import it, it throws errors in browsers.

- Uncaught ReferenceError: require is not defined

Microbundle doesn't redefine require(). I think it's designed for front-end-only modules. If you're set on microbundle, one solution would be to import jsep from 'jsep' and 'export= instead of module.exports=, but this would prevent older versions of node from using it. And additionally, using that way, imports all the functions directly under window.exports e.g. window.exports.parse().

[donmccurdy]

It looks like Microbundle expects the input source code to use ES modules. It still creates CJS-compatible outputs from that. I've updated accordingly. For the standalone script use case, this should work:

<script src="https://unpkg.com/jsep@0.3.4/build/jsep.js"></script>
<script src="https://unpkg.com/expression-eval@3.0.4/dist/expression-eval.umd.js"></script>
<script>

const fn = expressionEval.compile('a+3');
console.log('result: ', fn({a:4}));

</script>

[josh-hemphill]

Awesome, that works great.
BTW, I made a codepen that people could use to try out how it behaves with certain inputs. I ended up using something like it a lot to determine how to handle different edge cases and such.