Javascript String Assignment Operators

Question

How come I can use += on a string, but I cannot use -= on it?

For example...

var test = \"Test\";
var arr = \"⇔\"         


        

Answer 1

That's because the minus sign is not a valid String operator, whereas the plus sign is overloaded to handle both Numbers (addition operator) and Strings (concatenation operator).

What results were you hoping to get from this?