AI solution for JavaScript Quiz on BFE.dev
26. true or false
The code outputs the following by console.log:
true
true
true
true
true
false
true
true
Explanation:
-
[] == 0
compares an empty array to 0 using loose equality, which coerces the empty array into an empty string and 0 into a number. An empty string and 0 both have a falsy value, but since they're of different data types, they're not equal. However, when a falsy value is compared to a number, it's coerced into a number, thus resulting in 0. Therefore,[] == 0
becomes"" == 0
, which becomes0 == 0
, evaluating to true. -
[] == false
also uses loose equality, but this time the empty array is coerced into a falsy value (empty arrays are also falsy), and false is a falsy value. Both have the same type, so they're compared after conversion. Therefore,[] == false
becomes0 == 0
, which evaluates to true. -
!![]
uses the double negation operator (!!), which coerces any value into a boolean by first negating it, and then negating it again. Since an array is a truthy value, its negation is false, and the negation of that is true. Therefore,!![]
evaluates to true. -
[1] == 1
uses loose equality, and since the array has a single element, that element is gotten and compared to 1. Because loose equality converts arrays to strings and converts non-string values to strings,[1] == 1
becomes"1" == "1"
, which evaluates to true. -
!![1]
works like!![]
, and since any non-empty array is truthy,!![1]
also evaluates to true. -
Boolean([])
is a function call that returns the boolean value of the argument. Since an empty array is falsy,Boolean([])
evaluates to false. -
Boolean(new Boolean([]))
uses the Boolean constructor to create a boolean object, which is a truthy value, soBoolean(new Boolean([]))
evaluates to true. -
Boolean(new Boolean(false))
creates a boolean object with a value of false. Since any object is truthy,Boolean(new Boolean(false))
evaluates to true.