Quartz sync: May 6, 2024, 10:40 PM

content/20201026103714-javascript_async_functions.md

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+---
+id: 03f42b69-8321-443f-9d1d-fb7814999dd7
+title: JavaScript Async Functions
+---
+
+# Introduction
+
+Async Functions[^1] is a new feature implemented in
+[ES2017](20201026104538-es2017) to handle
+[promises](20200911154351-promises).
+
+# Syntax
+
+## Fulfilling a promise
+
+``` javascript
+async function asyncFunc() {
+  return 123;
+}
+
+asyncFunc().then((x) => console.log(x));
+// 123
+```
+
+## Rejecting a promise
+
+``` javascript
+async function asyncFunc() {
+  throw new Error("Problem!");
+}
+
+asyncFunc().catch((err) => console.log(err));
+// Error: Problem!
+```
+
+# Footnotes
+
+[^1]: <https://github.com/tc39/ecmascript-asyncawait>