Async Transform Function in JavaScript

async-transform.js

/***************************************************/

function asyncTransform( transforms, val, context ) {
  if (typeof val === 'undefined') {
    return v => asyncTransform(transforms, v, context);
  }
  const v = Promise.resolve(val);
  if (context) {
    transforms = transforms.map( t => v => t.call(context, v));
  }
  return transforms.reduce((p, t) => p.then(t), v);
}

/***************************************************/

// Use:
const funcs = [
  v => v+1,
  v => Promise.resolve(v*2), // some sync, some async
  v => v*v,
  v => Promise.resolve({foo:v})
];

const process = asyncTranform(funcs);

process(1).then( v => console.log(v) ) // { foo: 16 }