JavaScript Math floor()

The JavaScript Math.floor() function rounds down a number to the next smallest integer.

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

Return value from Math.floor()

  • 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.


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