## Introduction

Floats and doubles represent floating-point numbers - numbers with decimal points. While this type is *very* useful for a wide variety of environments, depending on what they're used for, we sometimes want to *round* them to a whole number - closest whole integer, up or down.

In this article, we will explore how to round double/float numbers (including strings) in JavaScript using built-in methods of the

`Math`

object.

### The *Math* Object

The `Math`

object is used to conduct commonplace mathematical operations. Because the `Math`

object is a static built-in object, you can't and won't need to initialize it - it can be invoked at any point as a static object with helper methods. It has a plethora of constants and techniques for doing mathematical operations, all of which may be accessed directly.

Let's look at some of the `Math`

object's handy methods for rounding doubles/floats in JavaScript!

*Math.round()*

`Math.round()`

is a function used to return the value of a floating-point number rounded to the nearest whole integer. Depending on the supplied float/double, `Math.round()`

either rounds up or down.

If the floating-point number is above or equal to `x.5`

- it's rounded *up* to the nearest integer. If the floating-point number is below `x.5`

, it's rounded *down* to the nearest integer:

```
Math.round(24.49); // 24
Math.round('29.5'); // 30
Math.round(72); // 72
Math.round(-40.51); // -41
```

*Math.floor()*

The `Math.floor()`

method is used to return the nearest whole integer that is less than or equal to a specified value. In layman's terms, the `floor()`

method rounds a number down and returns an integer result:

```
Math.floor(75.95); // 75
Math.floor(75.05); // 75
Math.floor(4); // 4
Math.floor('-65.05'); // -66
Math.floor(-65.95); // -66
```

**Note:** `Math.floor(null)`

returns 0, not a `NaN`

error.

*Math.ceil()*

The `Math.ceil()`

method rounds a number up to the nearest greatest integer. Simply said, it is used to round up a number and return an integer value:

```
Math.ceil(0.95); // 1
Math.ceil(7); // 7
Math.ceil('9.008'); // 10
Math.ceil(-0.95); // -0
Math.ceil(-7); // -7
Math.ceil(-9.008); // -10
```

**Note:** `Math.ceil(null)`

returns integer 0 and does not give a `NaN`

error.

*Math.trunc()*

While truncating isn't *rounding* - it's worth mentioning the `Math.trunc()`

method. It returns the whole integer of the number, by *truncating* (cutting off) the floating-point precision, regardless of whether the argument is positive or negative:

```
Math.trunc(38.37); // 38
Math.trunc(72.84); // 72
Math.trunc(0.123); // 0
Math.trunc(-0.13323); // -0
Math.trunc('-1.18923'); // -1
Math.trunc(NaN); // NaN
Math.trunc('john'); // NaN
Math.trunc(); // NaN
```

## Conclusion

In this short article, we've taken a look at how to round doubles/floats in JavaScript, with the help of `Math.round()`

, `Math.floor()`

, `Math.ceil()`

and `Math.trunc()`

.