1.2 KiB
1.2 KiB
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Truthy Value |
A truthy value is a value that translates to true when evaluated in a Boolean context.
All values are truthy unless they are defined as falsy (i.e. except for false
, 0
, ""
, null
, undefined
and NaN
).
Some interesting truthy values are:
'0' (a string containing a single zero) 'false' (a string containing the text “false”) [] (an empty array) {} (an empty object) function(){} (an “empty” function)
Rules:
false
,zero
and''
(empty strings) are all equivalent.null
andundefined
are equivalent to themselves and each other but nothing else.NaN
is not equivalent to anything – including another `NaN!Infinity
is truthy – but cannot be compared totrue
orfalse
!- An empty array(
[]
) is truthy – yet comparing withtrue
isfalse
and comparing withfalse
istrue
?!
A single value can therefore be used within conditions, e.g.
if (value) { // value is truthy } else { // value is falsy // it could be false, 0, '', null, undefined or NaN }
See also: falsy | MDN