HTML and CSS Reference
In-Depth Information
JavaScript program starts here.
The variable num is assigned 10 .
Output is sent to the browser.
The shortcut assignment operator, +=, adds 2 to the variable num. This is equiva-
lent to num = num + 1; .
The shortcut assignment operator, -=, subtracts 1 from the variable num. This is
equivalent to num = num - 1; .
The shortcut assignment operator, *, multiplies the variable num by 3. This is
equivalent to num = num * 3; .
The shortcut assignment modulus operator, %, yields the integer amount that re-
mains after the scalar num is divided by 5. The operator is called the modulus op-
erator or remainder operator. The expression var %= 5 is equivalent to num = num
% 5 ;.
JavaScript ends here. The output is shown in Figure 5.4.
Figure 5.4 Output from Example 5.4: Shortcut operators.
5.2.3 Autoincrement and Autodecrement Operators
To make programs easier to read, to simplify typing, and, at the machine level, to
produce more efficient code, the autoincrement (++) and autodecrement (- -) oper-
ators are provided.
The autoincrement operator performs the simple task of incrementing the value of its
operand by 1, and the autodecrement operator decrements the value of its operand by
1. The operator has two forms: the first form prefixes the variable with either ++ or - -
(e.g., ++x or - - x) ; the second form postfixes (places the operator after) the variable
name with either ++ or - - (e.g., x++ or x - -). For simple operations, such as x++ or
x- -, ++x or - -x, the effect is the same; both ++x and x++ add one to the value of x, and
both - - x and x - - subtract one from the value of x .
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