The +
operator can add or concatenate. Which
one it does depends on the types of the parameters. If either operand is an empty
string, it produces the other operand converted to a string. If both operands are
numbers, it produces the sum. Otherwise, it converts both operands to strings and
concatenates them. This complicated behavior is a common source of bugs. If you
intend +
to add, make sure that both operands are
numbers.
3.17.150.163