为什么这个表达式在javaScript中返回2？

Question

I would think you might get 0 , maybe because the strings are turned to 1's and the - operator causes a subtraction operation to take place?

"1" - - "1";

Thanks in advance!

Answer 1

这就是数学的工作原理

1 - (-1) = 1 + 1

Answer 2

The - casts the string to a number and also acts as a minus sign.

1 - (-1) = 1 + 1 = 2

Answer 3

1 - (-1) = 2. I dont see the issue? JavaScript will parse those as integers because of the minus sign, expecting math. It also happens if you multiply a numerical string by 1, aka the poor man's parseInt().