# Math.trunc()

## BaselineWidely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.

The `Math.trunc()` static method returns the integer part of a number by removing any fractional digits.

## Syntax

js
``````Math.trunc(x)
``````

`x`

A number.

### Return value

The integer part of `x`.

## Description

Unlike the other three `Math` methods: `Math.floor()`, `Math.ceil()` and `Math.round()`, the way `Math.trunc()` works is very simple. It truncates (cuts off) the dot and the digits to the right of it, no matter whether the argument is a positive or negative number.

Because `trunc()` is a static method of `Math`, you always use it as `Math.trunc()`, rather than as a method of a `Math` object you created (`Math` is not a constructor).

## Examples

### Using Math.trunc()

js
``````Math.trunc(-Infinity); // -Infinity
Math.trunc("-1.123"); // -1
Math.trunc(-0.123); // -0
Math.trunc(-0); // -0
Math.trunc(0); // 0
Math.trunc(0.123); // 0
Math.trunc(13.37); // 13
Math.trunc(42.84); // 42
Math.trunc(Infinity); // Infinity
``````

### Using bitwise no-ops to truncate numbers

Warning: This is not a polyfill for `Math.trunc()` because of non-negligible edge cases.

Bitwise operations convert their operands to 32-bit integers, which people have historically taken advantage of to truncate float-point numbers. Common techniques include:

js
``````const original = 3.14;
const truncated1 = ~~original; // Double negation
const truncated2 = original & -1; // Bitwise AND with -1
const truncated3 = original | 0; // Bitwise OR with 0
const truncated4 = original ^ 0; // Bitwise XOR with 0
const truncated5 = original >> 0; // Bitwise shifting by 0
``````

Beware that this is essentially `toInt32`, which is not the same as `Math.trunc`. When the value does not satisfy -231 - 1 < `value` < 231 (-2147483649 < `value` < 2147483648), the conversion would overflow.

js
``````const a = ~~2147483648; // -2147483648
const b = ~~-2147483649; // 2147483647
const c = ~~4294967296; // 0
``````

Only use `~~` as a substitution for `Math.trunc()` when you are confident that the range of input falls within the range of 32-bit integers.

## Specifications

Specification
ECMAScript Language Specification
# sec-math.trunc

## Browser compatibility

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