Falsy vs. Nullish Values in JavaScript
This is a quick summary on Falsy and Nullish values in JavaScript. JavaScript has 8 falsy values, and 2 nullish values. The two nullish values are also falsy, but the rest of the falsy values are not nullish.
Falsy Values
A falsy value is something that is considered as false when used in a boolean context. JavaScript uses Type Coercion to convert non-boolean values in boolean contexts (such as a conditional, or a loop) into boolean form. There are 8 falsy values:
| Value | Description |
|---|---|
false | The keyword false |
0 | Number 0 |
-0 | Negative number 0 |
0n | 0 in BigInt |
‘’, “” | Empty string |
null | Primitive null – no value |
undefined | Primitive undefined |
NaN | Not a Number |
Nullish Values
The two primitives null and undefined are known as nullish. Put simply, it means that they don’t have any value. They get converted to false via Type Coercion in a boolean context.
By above definitions, we see that nullish values are also falsy.