Configurations are similar to CSS in that they cascade from less specific to more specific. The config.util.getConfigSources(); method can be used to see all sources contributing to the ultimate configuration, and the order in which they were are applied.

This would allow a UI similar to a CSS inspector to show all source values, with strikethroughs for values overwritten by more specific cascading values.

[ { name: '/full/path/to/config/default.js',
    original: '\nvar config = {\n  siteName : \'default site name\',\n};\n\nconfig.email = {\n    subject : \'default subject\',\n}\n\nmodule.exports = config;\n',
    parsed: { siteName: 'default site name', email: [Object] } },
  { name: '/full/path/to/config/local.js',
    original: '\nvar config = {\n  siteName : \'local site name\',\n};\n\nmodule.exports = config;\n',
    parsed: { siteName: 'local site name' } },
  { name: '$NODE_CONFIG', parsed: { EnvOverride: [Object] } },
  { name: '--NODE_CONFIG argument',
    parsed: { EnvOverride: [Object] } } ]

Notice that in additon to full paths, some other special names are included: $NODE_CONFIG from the environment and --NODE_CONFIG argument from the command line.

While [Object] is shown here, the full objects are available in the actual output.