server-2.js

const Koa = require('koa');
const serve = require('koa-static');
const { get } = require('koa-route');

const app = new Koa();

app.use(
  get('/api/v1/peaks', ctx => {
    const data = require('./data/summits.json');
    ctx.body = data;
  })
);

app.use(serve('src/public'));

app.listen(3000);

server.js

const Koa = require('koa');
const serve = require('koa-static');
const { get } = require('koa-route');
// Note: you can use brackets as a shortcut… instead of _.get(), { get } is quicker.
// Good to save space / if you only need one thing; otherwise, importing all may be quicker.

const app = new Koa();

app.use(serve('src/public'));

// JSON endpoint, adapted from https://github.com/koajs/route
get('/api/v1/peaks', ctx => {
  const data = require('../src/data/summits.json') // maybe this should be in server/ innstead?
  ctx.body = data;
  // Does this work?
});

app.listen(3000);