JavaScript 2.0-The Complete Reference, Second ... - freecodingtutorial

Operators
JavaScript supports a variety of operators. Some of them, like those for arithmetic and
comparison, are easy for even those new to programming to understand. Others, like the
bitwise AND (&), increment (++), and some conditional (?:) operators, may be less obvious to
those who have not programmed before. Fortunately for readers of all levels, JavaScript
supports few operators that are unique to the language, and the language mimics C, C++, and
Java closely in both the kinds of operators it provides and their functionality.
Assignment Operator
Probably the most basic operator is the assignment operator (=), which is used to assign a
value to a variable. Often this operator is used to set a variable to a literal value, for example:
var bigPlanetName = "Jupiter";
var distanceFromSun = 483600000;
var visited = true;
Generally, the assignment operator is used to assign a value to a single variable, but it is
possible to perform multiple assignments at once by stringing them together with the =
operator. For example, the statement
var x = y = z = 7;
sets all three variables to a value of 7.
Assignments can also be used to set a variable to hold the value of an expression. For
example, this script fragment demonstrates how variables can be set to the sum of two literal
values as well as a combination of literals and variables:
var x = 12 + 5; // x set to 17
var a, b = 3; // a declared but not defined, b set to 3
a = b + 2; // a now contains 5
Arithmetic Operators
JavaScript supports all the basic arithmetic operators that readers should be familiar with,
including addition (+), subtraction (–), multiplication (*), division (/), and modulus (%, also known
as the remainder operator). Table 4-1 details all these operators and presents examples of
each.
Table 4-1: Basic Arithmetic Operators
Operator Meaning Example Result
+ Addition var x = 5, y = 7;
var sum;
sum = x+y;
– Subtraction var x = 5, y = 7;
var diff1, diff2;
diff1 = x–y;
diff2 = y–x;
Variable sum
contains 12.
Variable diff1
contains –2 while
variable diff2
contains 2.
* Multiplication var x = 8, y = 4; Variable product