Return value and chaining
Like most expressions, assignments like x = y have a return value. It
can be retrieved by e.g. assigning the expression or logging itLike most
expressions, assignments like x = y have a return value. It can be
retrieved by e.g. assigning the expression or logging it.
The return value matches the expression to the right of the = sign in
the “Meaning” column of the table above. That means that (x = y) returns
y, (x += y) returns the resulting sum x + y, (x **= y) returns the
resulting power x ** y, and so on. In the case of logical assignments,
(x &&= y), (x ||= y), and (x ??= y), the return value is that of the
logical operation without the assignment, so x && y, x || y, and x ?? y,
respectively.
Note that the return values are always based on the operands’ values
before the operation.
When chaining these expressions, each assignment is evaluated
right-to-left. Consider these examples:
-
w = z = x = y is equivalent to w = (z = (x = y)) or x = y; z = y; w =
y
-
z += x *= y is equivalent to z += (x *= y) or tmp = x * y; x *= y; z
+= tmp (except without the tmp).
Comparison operators
A comparison operator compares its operands and returns a logical value
based on whether the comparison is true. The operands can be numerical,
string, logical, or object values. Strings are compared based on
standard lexicographical ordering, using Unicode values. In most cases,
if the two operands are not of the same type, JavaScript attempts to
convert them to an appropriate type for the comparison. This behavior
generally results in comparing the operands numerically. The sole
exceptions to type conversion within comparisons involve the === and !==
operators, which perform strict equality and inequality comparisons.
These operators do not attempt to convert the operands to compatible
types before checking equality.
If you use the document.write() method method after the page has been
loaded, it will overwrite all the existing content in that document.
Check out the following example:
Arithmetic Operator
An arithmetic operator takes numerical values (either literals or
variables) as their operands and returns a single numerical value. The
standard arithmetic operators are addition (+), subtraction (-),
multiplication (*), and division (/). These operators work as they do in
most other programming languages when used with floating point numbers
(in particular, note that division by zero produces Infinity).
In addition to the standard arithmetic operations (+, -, *, /),
JavaScript provides the arithmetic operators listed in the following
table:
