Require Context

The context with webpack refers to the base folder in which modules are resolved. The primary context can be changed through the context option in your webpack.config.js.

Contexts can be generated on the fly as well using require.context(). This will create a new require method that operates within the constraints specified for the context. A useful example is when you would like to require all or certain tests within your test suite:

var requireTest = require.context('./tests', true, /_test\.js$/);

This will create a context with:

• ./tests as its base,
• true to recusively search sub-directories,
• and a regular expression /_test\.js$/ the file must pass to be include. In this case, the file must end with '_test.js'.

Now we can use this new require function to resolve our test file ./tests/bear_test.js:

var bearTest = requireTest('./bear_test.js');

Or more useful, retrieving a list of modules the context contains (require.keys()) to require all tests within the ./tests folder that end with _test.js:

var requireTest = require.context('./tests', true, /_test\.js$/);
requireTest.keys().forEach(requireTest);

Or setup to ignore certain tests:

var requireTest = require.context('./tests', true, /_test\.js$/);
var ignoredTests = [
  './ignoreme_test.js'
];
requireTest.keys().filter(function(testName) {
  return ignoredTests.indexOf(testName) === -1;
}).forEach(requireTest);

The require context is a very useful feature when integrating with a framework with a built-in method of resolving pieces, such as with Ember resolvers.