How is '2'+'2'-'2'= 20 in JavaScript?

Question

I was just randomly playing around JavaScript. The '2'+'2'-'2' input I given to it.

and the output is surprisingly 20.

console.log('2'+'2'-'2');

Now I am not getting it.

Does anyone explain is to me Why it is like this? How can be output of this equal to 20?

Answer 1

+ is both concatenation and addition. If any of the arguments are not numeric, then it's concatenation. Thus, '2' + '2' is '22' - just like "foo" + "bar" are "foobar", and just like 3 + {} is "3[object Object]".

- is only subtraction. No matter what its arguments are, they are coerced to numbers. Thus, '22' - '2' is evaluated as 22 - 2, which is 20.