`Math.ceil`

, `floor`

, and `trunc`

Examples¶

`Math.ceil`

¶

The general syntax for this method is:

```
Math.ceil(number)
```

This method rounds a decimal value UP to the next integer (hence the
*ceiling* reference in the name). Integer values remain the same.

`ceil`

also operates on arrays (see below).

Numerical strings can also be evaluated, but should be avoided as a best practice.

Example

1 2 3 4 5 6 7 | ```
console.log(Math.ceil(8.88));
console.log(Math.ceil(8.1));
console.log(Math.ceil(-3.9));
console.log(Math.ceil(5));
``` |

**Console Output**

```
9
9
-3
5
```

`Math.floor`

¶

The general syntax for this method is:

```
Math.floor(number)
```

This method is the opposite of `Math.ceil`

. It rounds a decimal value DOWN to
the previous integer. Integer values remain the same.

`floor`

also operates on arrays (see below).

Numerical strings can also be evaluated, but should be avoided as a best practice.

Example

1 2 3 4 5 6 7 | ```
console.log(Math.floor(8.88));
console.log(Math.floor(8.1));
console.log(Math.floor(-3.9));
console.log(Math.floor(5));
``` |

**Console Output**

```
8
8
-4
5
```

`Math.trunc`

¶

The general syntax for this method is:

```
Math.trunc(number)
```

This method removes any decimals and returns only the integer part of `number`

.

`trunc`

also operates on arrays (see below).

Numerical strings can also be evaluated, but should be avoided as a best practice.

Example

1 2 3 | ```
console.log(Math.trunc(8.88));
console.log(Math.trunc(10.000111));
``` |

**Console Output**

```
8
10
```

Note

At first glance, `Math.floor`

and `Math.trunc`

appear to do exactly the
same thing. However, a closer look shows that the two methods treat negative numbers
differently.

**Console Output**

## Combine with `map`

¶

When combined with the map array method, `ceil`

, `floor`

, and `trunc`

will operate on each entry in an array. The syntax for this is:

```
arrayName.map(Math.method)
```

Example

1 2 3 4 5 | ```
let numbers = [-2, 3.33, -4.44, 8.88];
console.log(numbers.map(Math.ceil));
console.log(numbers.map(Math.floor));
console.log(numbers.map(Math.trunc));
``` |

**Console Output**

```
[ -2, 4, -4, 9 ]
[ -2, 3, -5, 8 ]
[ -2, 3, -4, 8 ]
```