Pipe async functions
Performs left-to-right function composition for asynchronous functions.
- Use
Array.prototype.reduce()
and the spread operator (...
) to perform function composition usingPromise.prototype.then()
. - The functions can return a combination of normal values,
Promise
s or beasync
, returning throughawait
. - All functions must accept a single argument.
const pipeAsyncFunctions = (...fns) => arg => fns.reduce((p, f) => p.then(f), Promise.resolve(arg)); const sum = pipeAsyncFunctions( x => x + 1, x => new Promise(resolve => setTimeout(() => resolve(x + 2), 1000)), x => x + 3, async x => (await x) + 4 ); (async() => { console.log(await sum(5)); // 15 (after one second) })();