refactor: strictly typed

src/util/promise.ts

@@ -1,26 +1,15 @@
-/*
- * Call functions in serial until someone resolved.
- * @param iterable the array to iterate with.
- * @param iteratee returns a new promise.
- * The iteratee is invoked with three arguments: (value, index, iterable).
- */
-export function anySeries (iterable, iteratee) {
-  let ret: Promise<any> = Promise.reject(new Error('init'))
-  iterable.forEach(function (item, idx) {
-    ret = ret.catch(() => iteratee(item, idx, iterable))
-  })
-  return ret
-}
-
 /*
  * Call functions in serial until someone rejected.
  * @param {Array} iterable the array to iterate with.
  * @param {Array} iteratee returns a new promise.
  * The iteratee is invoked with three arguments: (value, index, iterable).
  */
-export function mapSeries (iterable, iteratee) {
-  let ret: Promise<any> = Promise.resolve('init')
-  const result = []
+export function mapSeries<T1, T2> (
+    iterable: T1[],
+    iteratee: (item: T1, idx: number, iterable: T1[]) => Promise<T2> | T2
+): Promise<T2[]> {
+  let ret = Promise.resolve(0)
+  const result: T2[] = []
   iterable.forEach(function (item, idx) {
     ret = ret
       .then(() => iteratee(item, idx, iterable))