Why is the answer 42?

Question

I'm trying to understand how this palindrome expression is giving 42. I know about operator precedence rules, but this is beyond my current Javascript level. How can I start?

alert ("The answer is " +

[(0>>(0==0))+([0]+[(0==0)+(0==0)]^0)]*[(0^[(0==0)+(0==0)]+[0])+((0==0)<<0)]

);

Answer 1

The basic elements are as follows:

0==0

This is true, which can be coerced in to 1.

a >> b

The right-shift operator. In this case, it's only used at the beginning of the expression as 0 >> 1 which evaluates to 0.

a^b

Bitwise XOR. Both usages above have either a or b are 0, and so the result is the non-zero operand, coerced into an integer.

[a] + [b]

String addition of a and b, evaluates to "ab"; if both a and b are numeric (e.g. [0]+[1] the result can be coerced into a numeric.

[a] * [b]

Multiplication can be performed on single element arrays, apparently. So this is equivalent to a*b.

Finally,

a << b

The left-shift operator; for positive integers this effectively multiplies by 2 to the power of b. In the expression above, this is used with b = 0, so the result is a, coerced into an integer.

If you apply the correct order of operations, you get out [2] * [21] which evaluates to 42.