D-E > eval

eval

eval

Availability

Flash Player 5 or later for full functionality. You can use the eval function when exporting to Flash Player 4, but you must use slash notation, and can only access variables, not properties or objects.

Usage

eval(expression);

Parameters

expression A string containing the name of a variable, property, object, or movie clip to retrieve.

Returns

Nothing.

Description

Function; accesses variables, properties, objects, or movie clips by name. If the expression is a variable or a property, the value of the variable or property is returned. If the expression is an object or movie clip, a reference to the object or movie clip is returned. If the element named in the expression cannot be found, undefined is returned.

In Flash 4, the eval function was used to simulate arrays; in Flash 5, it is recommended that you use the Array object to simulate arrays.

You can also use the eval function to dynamically set and retrieve the value of a variable or instance name. However, you can also do this with the array access operator ([]).

In Macromedia Flash MX, you cannot use the eval function to dynamically set and retrieve the value of a variable or instance name. However, you can use the set variable action in Macromedia Flash 5 or Macromedia Flash MX to dynamically set and retrieve the value of a variable or instance name. For example, replace the code

eval ("var" + i) = "first";

with this:

set ("var" + i, "first");

Example

The following example uses the eval function to determine the value of the expression "piece" + x. Because the result is a variable name, piece3, the eval function returns the value of the variable and assigns it to y:

piece3 = "dangerous";
x = 3; 

y = eval("piece" + x);
trace(y);

// Output: dangerous

See also

Array (object)