---
name: "up.element.styleNumber"
area: "API"
kind: "JavaScript function"
parent: "up.element module"
url: "https://unpoly.com/api/up.element.styleNumber"
---
<nav aria-label="Unpoly docs">[All docs](https://unpoly.com/index.md) · [up.element module](https://unpoly.com/api/up.element.md)</nav>

# up.element.styleNumber(element, prop)

Returns a [computed CSS property value](https://developer.mozilla.org/en-US/docs/Web/API/Window/getComputedStyle) for the given element, cast as a number.

The value is cast by removing the property's [unit](https://www.w3schools.com/cssref/css_units.asp) (which is usually `px` for computed properties). The result is then parsed as a floating point number.

Returns `undefined` if the property value is missing. Returns `NaN` if the value cannot be parsed as a number.

<nav aria-label="Contents">

#### Contents

- [Examples](#examples)
- [Parameters](#parameters)
- [Return value](#return-value)

</nav>

## Examples {#examples}

```js
let value = up.element.style(element, 'font-size')
// value is '16px'

value = up.element.styleNumber(element, 'font-size')
// value is 16
```

---

## Parameters {#parameters}

### element {#element}

(required)

Type: [Element](https://developer.mozilla.org/en-US/docs/Web/API/Element)

### prop {#prop}

(required)

A single property name in kebab-case.

Type: string

---

## Return value {#return-value}

The cast property value.

Type: number | undefined | NaN