# typeof

#### Availability

Flash Player 5.

#### Usage

    typeof(expression)

#### Parameters

`expression` A string, movie clip, button, object, or function.

#### Description

Operator; a unary operator placed before a single parameter. The `typeof` operator causes the Flash interpreter to evaluate `expression`; the result is a string specifying whether the expression is a string, movie clip, object, function, number, or Boolean value. The following table shows the results of the `typeof` operator on each type of expression:

Parameter | Output
String | `string`
Movie clip | `movieclip`
Button | `object`
Text field | `object`
Number | `number`
Boolean | `boolean`
Object | `object`
Function | `function`