in a value is an expression, it makes sense that variables, constants, and literals are all
expressions.
Operators
You can think of operators as the “verb” to an expression’s “noun.” That is, an expres‐
sion is a thing that results in a value; an operator is something you do to produce a
value. The outcome in both cases is a value. We’ll start our discussion of operators
with arithmetic operators: however you may feel about math, most people have some
experience with arithmetic operators, so they are an intuitive place to start.
Operators take one or more operands to produce a result. For
example, in the expression 1 + 2, 1 and 2 are the operands and + is
the operator. While operand is technically correct, you often see
operands called arguments.
Arithmetic Operators
JavaScript’s arithmetic operators are listed in
Table 5-1. Arithmetic operators
Operator Description
Example
+
Addition (also string
concatenation)
3 + 2 // 5
-
Subtraction
3 - 2 // 1
/
Division
3/2 // 1.5
*
Multiplication
3*2 // 6
%
Remainder
3%2 // 1
-
Unary negation
-x // negative x; if x is 5, -x will be -5
+
Unary plus
+x // if x is not a number, this will attempt conversion
++
Pre-increment
++x // increments x by one, and evaluates to the new
value
++
Post-increment
x++ // increments x by one, and evaluates to value of x
before the increment
Operators | 81
