The addition operator + can be used as a binary or unary operator.
As a binary operator, it sums two numbers.
As a unary operator, it simply returns the operand without applying any transformation.
Any argument passed as a string to the binary operator is automatically converted into a number.
The following two expressions with a binary operator return the same result.
6 + 4 "6" + "4"
Contributors: Alberto Ferrari, Marco Russo, Kenneth Barber