JavaScript Nullish_coalescing Guide
The nullish coalescing operator (??) returns the right side only if the left is null or undefined. The guide walks through ?? vs ||. `value ?? "default"` — uses default only if null/undefined. `value || "default"` — uses default for ANY falsy value (0, "", false). Use ?? for: default values where 0 or "" are valid. Use || for: fallbacks where all falsy values should use default. `a ?? b ?? c` — first non-nullish value. The guide is organized into 1 sections that build on each other, each pairing a prose explanation with runnable code. Related guides: Arrays, Strings, Numbers, Math, Date. This is one of 145 JavaScript guides on JS Reference — see the full list on the guides page. Practice what you learn in the JavaScript playground, and look up any unfamiliar term in the JavaScript glossary.