JavaScript · Language basics

Logical assignment

Assigns only when the operator’s condition passes. Useful for filling defaults.

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Syntax

x ??= 1; x ||= 2; x &&= 3;

Example

Try it

let options = { retries: 0 };
options.retries ??= 3;
options.timeout ||= 5000;
console.log(options);

Reference pages are the quick answer. The course explains the why, shows the full example and ends with a challenge.