Dynamic HTML: The Definitive Reference

Name

+= — NN 2 IE J1 ECMA 1

Synopsis

The add-by-value operator. This class of operator combines a regular assignment operator (=) with one of the many other operators to carry out the assignment by performing the stated operation on the left operand with the value of the right operand. For example, if a variable named a has a string stored in it, you can append a string to a with the += operator:

a += " and some more."

Without the add-by-value operator, the operation had to be structured as follows:

a = a + " and some more"

Table 11.2 shows all the assignment operators that function this way:

Table 11-2. Assignment Operators

Operator	Example	Equivalent
+=	a += b	a = a + b
-=	a -= b	a = a - b
*=	a *= b	a = a * b
/=	a /= b	a = a / b
%=	a %= b	a = a % b
<<=	a <<= b	a = a << b
>>=	a >>= b	a = a >> b
>>>=	a >>>= b	a = a >>> b
&=	a &= b	a = a & b
|=	a |= b	a = a | b
^=	a ^= b	a = a ^ b

Example

output += "<H1>Section 2</H1>"
total *= .95