Name

Math.floor() — round a number down

Synopsis

Math.floor(x)

Arguments

x

Any numeric value or expression.

Returns

The closest integer less than or equal to x.

Description

Math.floor() computes the floor function; in other words, it returns the nearest integer value that is less than or equal to the function argument.

Math.floor() rounds a floating-point value down to the closest integer. This behavior differs from that of Math.round(), which rounds up or down to the nearest integer. Also note that Math.floor() rounds negative numbers down (i.e., to be more negative), not up (i.e., closer to zero).

Example

a = Math.floor(1.99);    // Result is 1.0
b = Math.floor(1.01);    // Result is 1.0
c = Math.floor(1.0);     // Result is 1.0
d = Math.floor(-1.01);   // Result is -2.0

Get JavaScript: The Definitive Guide, 6th Edition now with the O’Reilly learning platform.

O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.