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# isFinite

The global **`isFinite()`** function determines whether the
passed value is a finite number. If needed, the parameter is first converted to a
number.

## Syntax

```js
isFinite(testValue)
```

### Parameters

- `testValue`
  - : The value to be tested for finiteness.

### Return value

**`false`** if the argument is (or will be coerced to) positive
or negative [`Infinity`](./Infinity.mdx) or [`NaN`](./NaN.mdx) or [`undefined`](./undefined.mdx);
otherwise, **`true`**.

## Description

`isFinite` is a function property of the global object.

You can use this function to determine whether a number is a finite number. The
`isFinite` function examines the number in its argument. If the argument is
`NaN`, positive infinity, or negative infinity, this method returns
`false`; otherwise, it returns `true`.
