: (type)

Availability

Flash Player 6.

Usage

[modifiers] [var] variableName:[type]
function functionName():[type] { ... }
function functionName(parameter1[:type], ... , parameterN[:type]) { ... }

Parameters

variableName An identifier for a variable.

type A native data type, class name that you have defined, or interface name.

functionName An identifier for a function.

parameter An identifier for a function parameter.

Description

Operator; specifies the variable type, function return type, or function parameter type. When used in a variable declaration or assignment, this operator specifies the variable's type; when used in a function declaration or definition, this operator specifies the function's return type; when used with a function parameter in a function definition, this operator specifies the variable type expected for that parameter.

Types are a compile-time-only feature. All types are checked at compile time, and errors are generated when there is a mismatch. (For more information, see Error Messages.) Mismatches can occur during assignment operations, function calls, and class member dereferencing using the dot (.) operator. To avoid type mismatch errors, use explicit typing (see Strict data typing).

Types that you can use include all native object types, classes and interfaces that you define, and Void and Function (which exist only as types, not as objects). The recognized native types are Array, Boolean, Button, Color, CustomActions, Date, Function, LoadVars, LocalConnection, Microphone, MovieClip, NetConnection, NetStream, Number, Object, SharedObject, Sound, String, TextField, TextFormat, Video, Void, XML, XMLNode, and XMLSocket.

Example

Usage 1: The following example declares a public variable named userName whose type is String and assigns an empty string to it.

public var userName:String = "";

Usage 2: This example demonstrates how to specify a function's parameter type. The following code defines a function named setDate() that takes a parameter named currentDate of type Date.

function setDate(currentDate:Date) {
   this.date = currentDate;
}

Usage 3: The following code defines a function named squareRoot() that takes a parameter named val of the Number type and returns the square root of val, also a Number type.

function squareRoot(val:Number):Number {
  return Math.sqrt(val);
}