Widely availableSupported across all major browsers. Safe to use in production.
Language core Widely available

Logical assignments

The logical AND assignment (&&=) and the logical OR assignment (||=) operators short-circuit the respective binary logical operators.

Language core

Overview

The logical AND assignment (&&=) and the logical OR assignment (||=) operators short-circuit the respective binary logical operators.

Browser support

Feature Desktop Mobile
Chrome
Edge
Firefox
Safari
Chrome Android
Safari iOS
logical_and_assignment
85
85
79
14
85
14
Other
javascript.operators.logical_or_assignment

The logical OR assignment (||=) operator only evaluates the right operand and assigns to the left if the left operand is falsy.
85
85
79
14
85
14
1+Supported (version) Not supported ※Has note Sub-feature descriptions sourced from MDN Web Docs (CC BY-SA 2.5)

Syntax

JAVASCRIPT 
let a = null;
a ??= 'default'; // a is 'default'

let b = '';
b ||= 'fallback'; // b is 'fallback'

let c = 'hello';
c &&= c.toUpperCase(); // c is 'HELLO'

Live demo

Orassignment (||=)

variable that falsevalue(emptycharacter, 0 etc). And onlyassignment..

PreviewFullscreen

Andassignment (&&=)

variable that truevalue. And onlyassignment..

PreviewFullscreen

Nullcombinebodyassignment (??=)

variable that null is undefined. And onlyassignment..

PreviewFullscreen

Use cases

  • Using Logical assignments

    The logical AND assignment (&&=) and the logical OR assignment (||=) operators short-circuit the respective binary logical operators.

Cautions

  • No specific concerns. Stable across all major browsers.

Accessibility

  • When updating the DOM dynamically, announce important changes to assistive technology with aria-live regions.

Related links

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