snippetjavascriptTip

What are truthy and falsy values in JavaScript?

Submitted by: @import:30-seconds-of-code·Mar 2, 2026·

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truthyjavascriptwhatfalsyandarevalues

Problem

JavaScript uses type coercion (implicit conversion of values from one data type to another) in Boolean contexts, such as conditionals. This means that values are considered either truthy (evaluate to true) or falsy (evaluate to false) depending on how they are evaluated in a Boolean context.
There are 6 values that are considered falsy in JavaScript:

The keyword false
The primitive value undefined
The primitive value null

Solution

Boolean(false);         // false
Boolean(undefined);     // false
Boolean(null);          // false
Boolean('');            // false
Boolean(NaN);           // false
Boolean(0);             // false
Boolean(-0);            // false
Boolean(0n);            // false

Boolean(true);          // true
Boolean('hi');          // true
Boolean(1);             // true
Boolean([]);            // true
Boolean([0]);           // true
Boolean([1]);           // true
Boolean({});            // true
Boolean({ a: 1 });      // true

The keyword false
The primitive value undefined
The primitive value null
The empty string ('', "")
The global property NaN
A number or BigInt representing 0 (0, -0, 0.0, -0.0, 0n)

Code Snippets

Boolean(false);         // false
Boolean(undefined);     // false
Boolean(null);          // false
Boolean('');            // false
Boolean(NaN);           // false
Boolean(0);             // false
Boolean(-0);            // false
Boolean(0n);            // false

Boolean(true);          // true
Boolean('hi');          // true
Boolean(1);             // true
Boolean([]);            // true
Boolean([0]);           // true
Boolean([1]);           // true
Boolean({});            // true
Boolean({ a: 1 });      // true

Context

From 30-seconds-of-code: truthy-falsy-values

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