Support function-type webpack configs

Function-type config support added in webpack 2 is super useful for making conditional configs. I wrote a tiny package that wraps webpack-merge and adds support for merging function configs, but it seems like it could very easily be a supported feature in webpack-merge.

Here’s how I’d envision it working:

// this needs a better name
const webpackMerge = require('webpack-merge/config-function');

const mergeStrategy = {/* ... */};

module.exports = webpackMerge.smartStrategy(mergeStrategy)(
  (env, options) => ({
    output: {
      filename: env.useHash ? '[name]-[].js' : '[name].js',
    },
  }),
  // ...
);

Merge functions imported from webpack-merge/config-function (name extremely WIP) would be the same merge functions provided by webpack-merge, but each function would return a config function instead of a config object. This returned function would take the parameters given to it by the webpack/webpack-dev-server CLI and pass them on to each config function. Functions would be called and the result would be merged using the merge functions from webpack-merge. Essentially, each merge function would be a lightweight wrapper around the parent merge function.

If this is something that’s of interest to you, I can cook up a PR.

This could very easily be extended to support Promise configs as well (as mentioned in #81).

[Joonpark13]

@5arias a workaround that I’m using right now is as follows:

in my webpack.dev.js I do

module.exports = env => merge(common(env), {
    ...
});

and in my webpack.common.js

module.exports = env = ({
    ...
    ---USE env HERE---
});

That said, I’d love to see this functionality added!

[vitalets]

@Joonpark13

@5arias a workaround that I’m using right now is as follows:

in my webpack.dev.js I do

module.exports = env => merge(common(env), {
    ...
});

and in my webpack.common.js

module.exports = env = ({
    ...
    ---USE env HERE---
});

That said, I’d love to see this functionality added!

This looks great but how do you run your builds from npm scripts? Having

"build:dev": "webpack --config webpack.dev.js --env development",
"build:prod": "webpack --config webpack.prod.js --env production"

looks like over-configuration: both dev / development and prod / production in command. The config itself should define all needed params.