JavaScript Fallback Values Explained: OR (||) vs Nullish

JavaScript Fallback Values Explained: OR (||) vs Nullish (??)

H
ey Devs 👋

JavaScript has a funny way of confusing developers — mostly because it gives us so many ways to do the same thing.
I got bored of writing if conditions everywhere, so I jumped into using the OR operator (||) and the nullish coalescing operator (??).

Most of the time, I was using these operators without fully understanding their true purpose. (Not really — but it makes the story more dramatic, hehe. )

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When I was a fresher, I saw these operators used everywhere. So let’s properly understand what they actually do.

1. Logical OR operator (||)

The logical OR operator returns the first truthy value, or the last value if nothing is truthy.

Falsy values in JavaScript include:

false, 0, "", null, undefined, NaN

Example

console.log("" || "default");     // "default"
console.log(0  || 42);            // 42
console.log(null || "fallback");  // "fallback"

Because 0 and "" are falsy, || replaces them.