JSFiddle - React, Tailwind, and code Playground

JavaScript

var promises = [Promise.resolve("a"), Promise.reject("b")];

Promise.all(promises.map(function(p, index) {
  return p.then(function(data) {
    console.log("inside .map()", data, "index", index)
    return data
  }, function(err) {
    throw new Error(err)
  })
}))
.then(function(complete) {
  console.log("all promises after .map()", complete)
}, function(err) {
  console.log("err", err)
})