From d8169280aa6fe1bc97c0c16f3ebc106aa355ad3c Mon Sep 17 00:00:00 2001
From: oleksii golikov <og@vi.ai>
Date: Mon, 9 Jul 2018 21:49:11 +0300
Subject: [PATCH] for await example

---
 JavaScript/a-for-await.js | 38 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 38 insertions(+)
 create mode 100644 JavaScript/a-for-await.js

diff --git a/JavaScript/a-for-await.js b/JavaScript/a-for-await.js
new file mode 100644
index 0000000..c445378
--- /dev/null
+++ b/JavaScript/a-for-await.js
@@ -0,0 +1,38 @@
+'use strict';
+
+async function * slowCounter() {
+  let counter = 0;
+  while (true) {
+    counter += 1;
+    yield new Promise((resolve) => {
+      setTimeout(() => resolve(counter), 1000);
+    })
+  }
+}
+
+async function * fastCounterDown() {
+  let counter = 1000000;
+  while (true) {
+    counter -= 1;
+    yield counter;
+  }
+}
+
+async function* zip (a, b) {
+  while (true) {
+    const [first, second] = await Promise.all([
+      a.next(),
+      b.next(),
+    ]);
+    
+    yield [first.value, second.value];
+  }
+}
+
+async function main () {
+  for await (let it of zip(slowCounter(), fastCounterDown())) {
+    console.log(it);
+  }
+}
+
+main();