Promise.each without bluebird

Question

I need using Promise.each on bluebird. But when I see the bundle files, I'm actually thinking twice using bluebird or not.

Can anyone give me an example using function like bluebird Promise.each without dependencies.

Answer 1

Sure:

Promise.each = function(arr, fn) { // take an array and a function
  // invalid input
  if(!Array.isArray(arr)) return Promise.reject(new Error("Non array passed to each"));
  // empty case
  if(arr.length === 0) return Promise.resolve(); 
  return arr.reduce(function(prev, cur) { 
    return prev.then(() => fn(cur))
  }, Promise.resolve());
}

Or with modern JS (Chrome or Edge or with a transpiler):

Promise.each = async function(arr, fn) { // take an array and a function
   for(const item of arr) await fn(item);
}