Truthy

In JavaScript, a truthy value is a value that is considered true when encountered in a Boolean context. All values are truthy unless they are defined as falsy. That is, all values are truthy except false, 0, -0, 0n, "", null, undefined, NaN, and document.all.

JavaScript uses type coercion in Boolean contexts.

Examples of truthy values in JavaScript (which will be coerced to true in boolean contexts, and thus execute the if block):

js
if (true);
if ({});
if ([]);
if (42);
if ("0");
if ("false");
if (new Date());
if (-42);
if (12n);
if (3.14);
if (-3.14);
if (Infinity);
if (-Infinity);

The logical AND operator, &&

If the first operand is truthy, the logical AND operator returns the second operand:

js
true && "dog";
// returns "dog"

[] && "dog";
// returns "dog"

See also