Add compiled outputs data for bundle, buildStatic methods

[sergei-startsev]

I've added the additional field outputs to the output of bundle, buildStatic methods. The field contains a sorted array of sources and appropriate source map data before merging them to the single bundle:

It allows to add plugins that can build custom bundles based on provided data, e.g. eval bundle:

eval(
   $__System.register(...);
   //# sourceMappingURL=moduleA.js.map
);
eval(...);
...
eval(...);

Here are more examples of different bundles that Webpack uses: devtool

[guybedford]

Thanks, I like the idea. How can the outputs object be used after being modified though? Can you provide an example of the sort of API you see this being used with?

[sergei-startsev]

Here is how it could be used for building eval bundles (each module is executed with eval, sourceMappingURL is also added to the eval):

return builder.buildStatic(url, {options}).then(function (output) {
    //resulted eval bundle with inline sourceMaps
    var bundle = "";
    output.outputs.forEach(function (el) {
        bundle += `
        eval("${JSON.stringify(el.source)}\n
            //# sourceMappingURL=data:application/json;base64,${new Buffer(el.sourceMaps).toString("base64")}"
        )\n`;
    });
    return bundle;
});

another example uses the custom algorithm for concatenation sourcemaps:

return builder.buildStatic(url, {options}).then(function (output) {
    //maps output to the expected format
    var files = output.outputs.map(function (el) {
        if (el.source) {
            //fixes source urls
            el.sourceMap.sources = el.sourceMap.sources.map(function (sourceURL) {
                return sourceURL.replace(/\\/g, "/");
            });
            return {
                code: el.source,
                map: el.sourceMap
            };
        } else {
            return {
                code: el,
                map: undefined
            };
        }
    });
    //builds concatenated bundle with inline sourcemaps
    var concatenated = concat(files, { delimiter: "\n" }).toStringWithSourceMap();
    var bundle = `${concatenated.code}\n
        //# sourceMappingURL=data:application/json;base64,${new Buffer(concatenated.map.toString()).toString("base64")}`;

    return bundle;
});

The idea is that you could customize your output bundle based on data in outputs field.

[guybedford]

I think it would be better to accept an outputs hook as a build option something like:

builder.bundle('x', {
  hook: {
    output: (outputs) => {
      return modifiedOutputs;
    }
  }
}).then(...);

That said, i'm weary to rush into a hook architecture on a whim without fully thinking it through as well.

[lastmjs]

Could this pull request relate to my questions here about a static build with the semantics of compile?