What Is the Optional Chaining Operator in JavaScript?

JavaScript optional chaining operator (?.)

Introduced in ES11, the optional chaining operator (?.) allows you to access values within a chain of connected objects where a reference or function in the chain could potentially be a nullish value (i.e. undefined or null). It has the following syntax:


You can use optional chaining when:

For example:

// ES11+
const name = posts?.[0]?.author?.name;
const result = callback?.();
// ...

The expression is evaluated left-to-right, and when/if the left operand evaluates to a nullish value, then the execution of the entire chain is stopped and evaluated to undefined (i.e. it short-circuit evaluates to undefined).

Without optional chaining you would have to check if each reference or function in the chain is a nullish value (which in some cases could mean a lot of nested checks and repetition). For example, one way to do that is using the logical AND operator (&&) like so:

const name = posts.length
    && posts[0]
    && posts[0].author
    && posts[0].author.name
const result = callback && callback();
// ...

Here, the logical AND operator would return the first falsy value, or the last operand if there's no falsy value.

Hope you found this post useful. It was published (and was last revised ). Please show your love and support by sharing this post.