How to get the sign from a variable?

Question

JavaScript

https://jsfiddle.net/vve3egdy/
the calculate(str) call takes a string like "1 + 2" with a hard-coded "NUM operation NUMBER" format (one space around the operation) and returns the result. How can I get the sign that is stored in the sign property?

Answer 1

eval('1 + 2')

Answer 2

In your code via calc.sign