If the variable is set to anything except a falsey value, the test will evaluate to true.
Source: wiktionary
Falsey
Synonyms for "falsey"
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Sample sentences
4 total sentences available.
In JavaScript, as well as the true or false Boolean values, other types of variables can be said to be truthy or falsey.
Source: wiktionary
To remember which values are truthy and which are falsey, just memorize the five falsey values - undefined, null, 0, "" and NaN -- and remember that everything else is truthy.
Source: wiktionary
Clojure uses the Boolean operators or and and. or returns either the first truthy value or the last value, and returns the first falsey value or, if no values are falsey, the last truthy value.
Source: wiktionary
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Data sourced from Wiktionary, WordNet, CMU, and other open linguistic databases. Updated March 2026.