JavaScript tutorial:
+ Operator

The (+) operator is use to sum two numbers or perform string concatenation.

Syntax

result = expression1 + expression2

The + operator syntax has these parts:

Part	Description
result	Any variable.
expression1	Any expression.
expression2	Any expression.

Example

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.

For information on when a run-time error is generated by the + operator, see the Operator Behavior table.

See also: += Operator, Operator Behavior, Operator Precedence, Operator Summary