在module.exports之前等待异步功能

Question

I have a NextJS app and am using next-routes to handle all routing.

My routing module currently looks like this:

const routes = require('next-routes')();
const { getEntries } = require('../data/contentful');

module.exports = async () => {
  const globalSettings = await getEntries({
    content_type: 'globalSettings',
  });

  routes
    .add('caseStudies', `/${globalSettings.fields.caseStudiesSlug}`, 'caseStudies')
    .add('caseStudy', `/${globalSettings.fields.caseStudiesSlug]}/:slug`, 'caseStudy')
    .add('home', `/`, 'index')
    .add('page', `/:slug*`, 'page'));

  return routes;
};

I can get this working for server side, but to use next-routes on client side, I need this module to immediately return the routes object rather than an async function. eg

const routes = require('next-routes')();
const { getEntries } = require('../data/contentful');

// Do this first, then module.exports
const globalSettings = await getEntries({
  content_type: 'globalSettings',
});

module.exports = routes
  .add('caseStudies', `/${globalSettings.fields.caseStudiesSlug}`, 'caseStudies')
  .add('caseStudy', `/${globalSettings.fields.caseStudiesSlug]}/:slug`, 'caseStudy')
  .add('home', `/`, 'index')
  .add('page', `/:slug*`, 'page'));

This doesn't work because await must be inside an async function. How can I complete my async API call before doing my module.exports of the routes object?

Answer 1

This is a special case of this renowned problem . Synchronous code can be transformed to asynchronous but not vice versa.

As shown in this similar answer , promises should be used up to application entry point if needed:

module.exports = (async () => {
  const globalSettings = await getEntries({
    content_type: 'globalSettings',
  });

  return routes
  .add('caseStudies', `/${globalSettings.fields.caseStudiesSlug}`, 'caseStudies')
  .add('caseStudy', `/${globalSettings.fields.caseStudiesSlug]}/:slug`, 'caseStudy')
  .add('home', `/`, 'index')
  .add('page', `/:slug*`, 'page'));
})();

This module also exports a promise so it needs to be chained in a module that depends on it.

There is a proposal for top-level await that is intended to provide syntactic sugar for this recipe.