Flash Player 7.
throw expression
Action; generates ("throws") an error that can be handled ("caught") by a catch
code block. If an exception is not caught by a catch
statement, the string representation of the thrown value is sent to the Output window.
expression
An ActionScript expression or object.
In this example...
function GetSquareRoot(Number:val) { try { // Calculate the square root of the val parameter if (val < 0 || isNaN(val) || !isFinite(val)) { throw new SquareRootException(); } return Math.sqrt(val); } catch (e) { // Display error message if(e instanceof SquareRootException) { trace("Square root failed; number may be out of range."); } else { trace("An unknown error occurred") } } function SquareRootException() { }