JavaScript Nullish Assignment Operators Guide

Logical assignment operators combine logical operations with assignment for cleaner code. Here's how to use them.

Nullish Coalescing Assignment (??=)#

Loading code block...

Best Practices#

Usage:
✓ ??= for null/undefined defaults
✓ ||= for falsy defaults
✓ &&= for conditional updates
✓ Initialize object properties

Patterns:
✓ Lazy initialization
✓ Cache population
✓ Default parameters
✓ Object property defaults

Prefer ??= when:
✓ 0 is a valid value
✓ '' is a valid value
✓ false is a valid value
✓ Only null/undefined should trigger

Avoid:
✗ Complex chaining
✗ Side effects in right-hand side
✗ Confusion with similar operators
✗ Overusing when simple = works

Logical assignment operators provide concise syntax for conditional assignments. Use ??= when only null or undefined should trigger assignment, ||= when any falsy value should trigger, and &&= when you want to replace truthy values. They're particularly useful for setting defaults, lazy initialization, and normalizing data.

JavaScript Nullish Assignment Operators Guide

Nullish Coalescing Assignment (??=)#

Logical OR Assignment (||=)#

Logical AND Assignment (&&=)#

Object Property Defaults#

Function Parameters#

Lazy Initialization#

Array Operations#

State Management#

DOM Manipulation#

API Response Handling#

Comparison Table#

Best Practices#

Conclusion#

Share this article

Related articles

JavaScript Nullish Coalescing Guide

Regular Expressions: A Practical JavaScript Guide

Functional Programming Patterns in JavaScript