AI solution for JavaScript Quiz on BFE.dev
112. Symbol

The code below outputs the following by console.log:

false
true
1

The first console.log checks if the symbol variable is a key in the object a, which is false because symbols are not enumerable and cannot be accessed using in operator. The second console.log checks if the string 'BFE' is a key in the object a, which is true because it is a valid property key. And the third console.log checks the length of the array returned by Object.keys(a), which is 1 because only the property 'BFE' was added to the object a using a string key.