Полезная информация

Microsoft® JScript™
+= Operator
 Language Reference 
Version 1 

See Also

Used to increment a variable by a specified amount.
result += expression

The += operator syntax has these parts:

Part Description
result Any variable.
expression Any expression.

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.

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

© 1997 Microsoft Corporation. All rights reserved. Terms of Use.