systemjs/docs/meta.md

Meta Configuration

The ES6 module loader uses a special metadata object that is passed between hooks.

An example of meta config is the module format of a module, which is stored at metadata.format.

The meta extension opens up this object for setting defaults through System.meta as well as inline module syntax.

In this way, we can specify the module format of a module through config:

  System.meta['some/module'] = {
    format: 'amd'
  };

  System.import('some/module') // always loaded as AMD even if it is a UMD module

Or the module can even specify its own meta:

some/module.js

  "format amd";

  if (typeof module != 'undefined' && module.exports)
    module.exports = 'cjs';
  else
    define(function() { return 'amd' });

Since it is impossible to write 100% accurate module detection, this inline format hint provides a useful way of informing the module format of a module.

The format options are - register, es6, amd, cjs, global.