---
name: "up.util.isBlank"
area: "API"
kind: "JavaScript function"
parent: "up.util module"
url: "https://unpoly.com/api/up.util.isBlank"
---
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# up.util.isBlank(value)

Returns whether the given argument is considered to be blank.

By default, this function returns `true` for:

- `undefined`
- `null`
- Empty strings
- Empty arrays
- A plain object without own enumerable properties

All other arguments return `false`.

To implement blank-ness checks for user-defined classes, see [`up.util.isBlank.key`](https://unpoly.com/api/up.util.isBlank.key.md).

---

## Parameters {#parameters}

### value {#value}

(required)

The value to check.

Type: any

---

## Return value {#return-value}

Whether the value is blank.

Type: boolean