Rename js snippets

snippets/js/s/chain-async-functions.md

@@ -0,0 +1,40 @@
+---
+title: Chain async functions
+type: snippet
+language: javascript
+tags: [function]
+cover: tram-car
+dateModified: 2020-09-15T16:28:04+03:00
+---
+
+Chains asynchronous functions.
+
+- Loop through an array of functions containing asynchronous events, calling `next` when each asynchronous event has completed.
+
+```js
+const chainAsync = fns => {
+  let curr = 0;
+  const last = fns[fns.length - 1];
+  const next = () => {
+    const fn = fns[curr++];
+    fn === last ? fn() : fn(next);
+  };
+  next();
+};
+```
+
+```js
+chainAsync([
+  next => {
+    console.log('0 seconds');
+    setTimeout(next, 1000);
+  },
+  next => {
+    console.log('1 second');
+    setTimeout(next, 1000);
+  },
+  () => {
+    console.log('2 second');
+  }
+]);
+```