JavaScript Math trunc() Method

JavaScript Math trunc() is a “static method that returns the integer part of a number by removing any fractional digits”. The Math.trunc() method removes the decimals, but it does NOT round the number.

Syntax

Math.trunc(number) 

Parameter(s)

number: It is the floating-point number whose integral part is to be returned.

Return Value

The integral part of x by removing the part after the decimal point.

Example 1: How to Use Math.trunc() Method

let a = 12.25;
let b = -6.3;
let c = 0.35;
let d = -0.2;
let e = [4.3]; // array with single element

console.log(Math.trunc(a));
console.log(Math.trunc(b));
console.log(Math.trunc(c));
console.log(Math.trunc(d));
console.log(Math.trunc(e));

Output

12
-6
0
-0
4

Example 2: Math.trunc() with Non-numeric function

The following example shows the cases where NaN is returned.

let a = "Hello, world"; // non-numeric string
let b; // empty variable
let c = [1, 2, 3, 4]; // array with more than one elements
let d = {}; // empty object

console.log(Math.trunc(a));
console.log(Math.trunc(b));
console.log(Math.trunc(c));
console.log(Math.trunc(d));

Output

NaN
NaN
NaN
NaN

Example 3: Math.trunc() with null and empty values

The following example demonstrates the cases where zero is returned.

let a = null;
let b = ""; // empty string
let c = []; // empty array

console.log(Math.trunc(a));
console.log(Math.trunc(b));
console.log(Math.trunc(c));

Output

0
0
0

Example 4: Math.trunc() with Numeric String

let string = "21.1993";

// trunc() with string argument
let value = Math.trunc(string);
console.log(value); 

Output

21

Browser compatibility

1. Google Chrome 38 and above
2. Firefox 25 and above
3. Opera 25 and above
4. Safari 8 and above
5. Edge 12 and above

That’s it.