Math.round()
The Math.round()
function returns the value of a number
rounded to the nearest integer.
Syntax
Math.round(x)
Parameters
x
-
A number.
Return value
The value of the given number rounded to the nearest integer.
Description
If the fractional portion of the argument is greater than 0.5, the argument is rounded
to the integer with the next higher absolute value. If it is less than 0.5, the argument
is rounded to the integer with the lower absolute value. If the fractional portion is
exactly 0.5, the argument is rounded to the next integer in the direction of +∞.
Note that this differs from many languages' round()
functions,
which often round this case to the next integer away from zero,
instead giving a different result in the case of negative numbers with a fractional part
of exactly 0.5.
Because round()
is a static method of Math
, you always use it
as Math.round()
, rather than as a method of a Math
object you
created (Math
has no constructor).
Examples
Using round
Math.round( 20.49); // 20
Math.round( 20.5 ); // 21
Math.round( 42 ); // 42
Math.round(-20.5 ); // -20
Math.round(-20.51); // -21
Specifications
Specification |
---|
ECMAScript Language Specification # sec-math.round |
Browser compatibility
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