Addition Assignment Operator (+=) (JScript 5.6)

Adds the value of an expression to the value of a variable and assigns the result to the variable.


result += expression

Arguments

Using this operator is exactly the same as specifying:

result = result + expression

The underlying subtype of the expressions determines the behavior of the += operator.

If	Then
Both expressions are numeric or Boolean	Add
Both expressions are strings	Concatenate
One expression is numeric and the other is a string	Concatenate