JavaScript Math round()

In this tutorial, we will learn about the JavaScript Math.round() function with the help of examples.

The Math.round() function returns the number rounded to the nearest integer. That is, 3.87 is rounded to 4 and 3.45 is rounded to 3.

Example

let number = 3.87;

// round the number to nearest integer let roundedNumber = Math.round(number);
console.log(roundedNumber); // Output: 4

Math.round() Syntax

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

Math.round(x)

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


Math.round() Parameters

The Math.round() function takes in:

  • x - A number

Return value from Math.round()

Math.round() returns the value of the number rounded to the nearest integer as follows:

  • If the fractional portion > 0.5, x is rounded to integer with higher absolute value.
  • If the fractional portion < 0.5, x is rounded to integer with lower absolute value.
  • If the fractional portion = 0.5, x is rounded to the next integer in the direction of +∞.

Example: Using Math.round()

// using Math.round()
var num = Math.round(1.8645);
console.log(num); // 2 var num = Math.round(10.49); console.log(num); // 10
var num = Math.round(4.5);
console.log(num); // 5 var num = Math.round(-4.5); console.log(num); // -4 // Returns 0 for null
var num = Math.round(null);
console.log(num); // 0 // Returns NaN for non-numeric types
var num = Math.round("JavaScript");
console.log(num); // NaN

Output

2
10
5
-4
0
NaN

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


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