Koa's use of promises via async functions does make a very clear declarative syntax when it comes to common scenarios involving asynchronous operations.
For instance, let's consider our routes/index.js file, imagine we had to look up the title from a database.
With async/await it would look something like the following:
const router = require('koa-router')()
router.get('/', async function (ctx, next) {
const title = await pretendDbLookup('title')
ctx.body = `
<html>
<head>
<title> ${title} </title>
<link rel="stylesheet" href="styles.css">
</head>
<body>
<h1> ${title} </h1>
<p> Welcome to ${title} </p>
</body>
</html>
`
})
function pretendDbLookup () {
return Promise.resolve('Koa')
}
module.exports = router
We can check this by copying the app folder from the main recipe to async-ops-app and placing the previous code in routes/index.js.
As long as the asynchronous operation returns a promise, we can use await inside Koa middleware and route handlers to perform asynchronous operations in a syntactically aesthetic manner. On a side note, pretendDbLookup could have been written as async function pretendDbLookup () { return 'Koa' } and the net result would be the same (a promise that resolves to the string Koa).