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snippets/articles/s/javascript-nullish-coalescing-optional-chaining.md

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+---
+title: How can I use optional chaining and nullish coalescing in my JavaScript project?
+shortTitle: Optional chaining and nullish coalescing
+type: question
+language: javascript
+tags: [type]
+author: chalarangelo
+cover: purple-leaves
+excerpt: JavaScript ES2020 introduced optional chaining and nullish coalescing. Learn everything you need to know with this quick guide.
+dateModified: 2021-06-12T19:30:41+03:00
+---
+
+JavaScript ES2020 introduced some new features that help us write cleaner code. Let's take a quick look at two of them that aim to make working with objects and variables a lot easier.
+
+### Optional chaining
+
+The [optional chaining operator](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Optional_chaining) (`?.`) allows us to access deeply nested object properties without having to validate each reference in the nesting chain. In case of a reference being nullish (`null` or `undefined`) the optional chaining operator will short-circuit, returning `undefined`. The optional chaining operator can also be used with function calls, returning `undefined` if the given function does not exist.
+
+The resulting code is shorter and simpler, as you can see below:
+
+```js
+const data = getDataFromMyAPI();
+
+// Without optional chaining
+const userName = data && data.user && data.user.name;
+const userType = data && data.user && data.user.type;
+data && data.showNotifications && data.showNotifications();
+
+// With optional chaining
+const userName = data?.user?.name;
+const userType = data?.user?.type;
+data.showNotifications?.();
+```
+
+### Nullish coalescing
+
+In the same spirit, the [nullish coalescing operator](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Nullish_coalescing_operator) (`??`) is a logical operator that allows us to check for nullish (`null` or `undefined`) values, returning the right-hand side operand when the value is non-nullish, otherwise returning the left-hand side operand.
+
+Apart from cleaner code, this operator might spare us some headaches related to falsy values:
+
+```js
+const config = getServerConfig();
+
+// Without nullish coalescing
+const port = config.server.port || 8888;
+// Oops! This will be true even if we pass it false
+const wrongkeepAlive = config.server.keepAlive || true;
+// We'll have to explicitly check for nullish values
+const keepAlive =
+  (config.server.keepAlive !== null & config.server.keepAlive !== undefined)
+  ? config.server.keepAlive : true;
+
+// With nullish coalescing
+const port = config.server.port ?? 8888;
+// This works correctly
+const keepAlive = config.server.keepAlive ?? true;
+```
+
+**Note:** Keep in mind that both features are quite new, so their support might not be great just yet (around 80% at the time of writing [[1]](https://caniuse.com/#feat=mdn-javascript_operators_optional_chaining)[[2]](https://caniuse.com/#feat=mdn-javascript_operators_nullish_coalescing)).