YouTipJsref Trunc
## JavaScript Math.trunc() Method
The `Math.trunc()` method is a built-in JavaScript function used to return the integer part of a number by removing any fractional (decimal) digits.
Unlike other rounding methods, `Math.trunc()` does not round the number up or down; it simply truncates (cuts off) the decimal point and everything to the right of it.
---
## Syntax
```javascript
Math.trunc(x)
```
### Parameter Values
| Parameter | Description |
| :--- | :--- |
| `x` | Required. A number or any value that can be converted into a numeric value. |
### Return Value
| Type | Description |
| :--- | :--- |
| `Number` | The integer part of the given number. Returns `NaN` if the argument cannot be converted to a number. |
---
## Browser Support
`Math.trunc()` is an ES6 (ECMAScript 2015) feature and is fully supported in all modern browsers:
| Chrome | Edge | Firefox | Safari | Opera |
| :---: | :---: | :---: | :---: | :---: |
| Yes | Yes | Yes | Yes | Yes |
---
## Basic Examples
### Example 1: Truncating Positive Numbers
```javascript
let result = Math.trunc(8.76);
console.log(result);
// Output: 8
```
### Example 2: Truncating Negative Numbers
```javascript
let result = Math.trunc(-8.76);
console.log(result);
// Output: -8
```
---
## Comprehensive Examples
The following examples demonstrate how `Math.trunc()` behaves with different types of inputs, including positive numbers, negative numbers, numeric strings, and non-numeric values:
```javascript
Math.trunc(13.37); // Returns 13
Math.trunc(42.84); // Returns 42
Math.trunc(0.123); // Returns 0
Math.trunc(-0.123); // Returns -0
Math.trunc("-1.123"); // Returns -1 (string is implicitly converted to a number)
Math.trunc(NaN); // Returns NaN
Math.trunc("foo"); // Returns NaN (string cannot be converted to a number)
Math.trunc(); // Returns NaN (undefined argument)
```
---
## Technical Considerations & Comparisons
### `Math.trunc()` vs. Other Rounding Methods
It is important to understand how `Math.trunc()` differs from other `Math` methods like `Math.floor()`, `Math.ceil()`, and `Math.round()`—especially when dealing with negative numbers.
| Input | `Math.trunc()` (Truncates) | `Math.floor()` (Rounds Down) | `Math.ceil()` (Rounds Up) | `Math.round()` (Rounds to Nearest) |
| :--- | :---: | :---: | :---: | :---: |
| **`3.7`** | `3` | `3` | `4` | `4` |
| **`3.2`** | `3` | `3` | `4` | `3` |
| **`-3.2`** | `-3` | `-4` | `-3` | `-3` |
| **`-3.7`** | `-3` | `-4` | `-3` | `-4` |
### Polyfill for Older Environments (Pre-ES6)
If you need to support legacy environments (like Internet Explorer) that do not support `Math.trunc()`, you can use the following polyfill:
```javascript
if (!Math.trunc) {
Math.trunc = function(v) {
v = Number(v);
return v < 0 ? Math.ceil(v) : Math.floor(v);
};
}
```