# Math.trunc()

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

## Syntax

Math.trunc(x)

x
A number.

### Return value

The integer part of the given number.

## 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.

The argument passed to this method will be converted to number type implicitly.

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).

## Polyfill

if (!Math.trunc) {
Math.trunc = function(v) {
v = +v;
if (!isFinite(v)) return v;

return (v - v % 1)   ||   (v < 0 ? -0 : v === 0 ? v : 0);

// returns:
//  0        ->  0
// -0        -> -0
//  0.2      ->  0
// -0.2      -> -0
//  0.7      ->  0
// -0.7      -> -0
//  Infinity ->  Infinity
// -Infinity -> -Infinity
//  NaN      ->  NaN
//  null     ->  0
};
}

or:

if (!Math.trunc) {
Math.trunc = function (v) {
return v < 0 ? Math.ceil(v) : Math.floor(v);
};
}

## Examples

### Using Math.trunc()

Math.trunc(13.37);    // 13
Math.trunc(42.84);    // 42
Math.trunc(0.123);    //  0
Math.trunc(-0.123);   // -0
Math.trunc('-1.123'); // -1
Math.trunc(NaN);      // NaN
Math.trunc('foo');    // NaN
Math.trunc();         // NaN

## Specifications

Specification
ECMAScript (ECMA-262)
The definition of 'Math.trunc' in that specification.

## Browser compatibility

Update compatibility data on GitHub
Desktop Mobile Server Chrome Edge Firefox Internet Explorer Opera Safari Android webview Chrome for Android Firefox for Android Opera for Android Chrome Full support 38 Edge Full support 12 Firefox Full support 25 IE No support No Opera Full support 25 Safari Full support 8 WebView Android Full support 38 Chrome Android Full support 38 Firefox Android Full support 25 Opera Android Full support 25 Safari iOS Full support 8 Samsung Internet Android Full support 3.0 nodejs Full support 0.12

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