JavaScript Math floor()

let number = 38.8;

// round number to nearest smallest number
let roundedNumber = Math.floor(number);
console.log(roundedNumber);

// Output: 38

Math.floor() Syntax

The syntax of the Math.floor() function is:

Math.floor(x)

floor(), being a static method, is called using the Math class name.

Math.floor() Parameters

The Math.floor() function takes in:

• x - A number

Math.floor() Return Value

• Returns the largest integer less than or equal to a given number.
• Returns 0 for null.

Example: Using Math.floor()

// using Math.floor()

var num = Math.floor(1.8645);
console.log(num); // 1

var num = Math.floor(-0.456);
console.log(num); // -1

var num = Math.floor("4");
console.log(num); // 4

// Returns 0 for null
var num = Math.floor(null);
console.log(num); // 0

// Returns NaN for non-numeric types
var num = Math.floor("JavaScript");
console.log(num); // NaN

var num = Math.floor(NaN);
console.log(num); // NaN

Output

1
-1
4
0
NaN
NaN

Note: Math.floor() returns 0 for null rather than NaN.

Recommended readings:

• JavaScript Math ceil()
• JavaScript Math round()