AI solution for JavaScript Quiz on BFE.dev
14. Addition vs Unary Plus

The output for the code above is:

3
3
3
12
3
12
3
2
2
1true
1NaN
1
1
1null
1NaN
NaN
NaN
1undefined
NaN
1undefined
NaN
NaN

Explanation:

• The first three lines are simple addition expressions and output the expected result.
• In line 4, '2' is concatenated to 1 (a string and a number) to get '12'.
• In line 5, the plus operator before the string '2' converts it to a number and we get 3 as the result.
• Lines 6-7 are similar to lines 4-5, just with different order of operands.
• In lines 8-9, true is converted to 1 and added to 1 to get 2, but the second statement has a plus operator before true, which converts it to a number (1) and then adds 1 to get 2 as well.
• Lines 10-11 are string concatenation with true converted to a string ('true') in the first line, and in the second line, the plus operator before true converts it to a number (1) and then is added to the string '1' to get '1true'.
• In lines 12-13, null is converted to 0 and added to 1 to get 1, but the second statement has a plus operator before null, which converts it to a number (0) and then adds 1 to get 1 as well.
• Lines 14-15 are similar to lines 4-5, just with null instead of '2'.
• In lines 16-17, undefined is converted to NaN and added to 1, resulting in NaN.
• Lines 18-19 are similar to lines 8-9, just with undefined instead of true.
• Line 20 has three plus operators before undefined, which is equivalent to +(+(+undefined)) or NaN.