The best way to use magic-regexp is by making use of the included build-time transform.

const regExp = createRegExp(exactly('foo/test.js').after('bar/'))
// => gets _compiled_ to
const regExp = /(?<=bar\/)foo\/test\.js/

Of course, this only works with non-dynamic regexps. Within the createRegExp block you have to include all the helpers you are using from magic-regexp - and not rely on any external variables. This, for example, will not statically compile into a RegExp, although it will still continue to work with a minimal runtime:

const someString = 'test'
const regExp = createRegExp(exactly(someString))