Refactor asyncMapStrict not to use async

It doesn't use async/await, but is not suitable for use with synchronous functions

Author: wojtekmaj

src/map_strict.js

@@ -1,12 +1,13 @@
-export default async function asyncMapStrict(arr, fn) {
-  const result = [];
-
-  for (let idx = 0; idx < arr.length; idx += 1) {
-    const cur = arr[idx];
-
-    // eslint-disable-next-line no-await-in-loop
-    result.push(await fn(cur, idx, arr));
-  }
-
-  return result;
+export default function asyncMapStrict(arr, fn) {
+  return new Promise((resolve) => {
+    const result = [];
+    arr.reduce(
+      (promise, cur, idx) => promise
+        .then(() => fn(cur, idx, arr)
+          .then((res) => {
+            result.push(res);
+          })),
+      Promise.resolve(),
+    ).then(() => resolve(result));
+  });
 }