Truthy - MDN Web Docs Glossary: Definitions of Web-related terms 编辑

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 (i.e., except for false, 0, -0, 0n, "", null, undefined, and NaN).

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):

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)

Specifications

See also

• Falsy
• Coercion
• Boolean