Can Javascript Ninja explain this : alert(eval('2*2' + 4)); // 48

Question

alert(eval('2*2' + 4)); // 48
I came across this in a challenge.
The result is unbelievable because I expect 8 to be the answer.
Is Javascript cheating on me?

Answer 1

'2*2' is a string, so the + operator is actually concatenating that 4 onto the end, so you get "2*24". That evaluates to 48.

You'd be right if the parentheses were a little bit different. E.g., eval('2*2') + 4 = 8

Answer 2

To be more clear, as the eval() function takes a string as input, it converts it's input into a single string thus making the input 2*24 in this case.