Edittext and onChanging event

I think using either onChange or onChanging to control what the user can enter into the control is less than ideal. With onChanging the use does get feedback that an incorrect char was entered but the text insertion is changed( as noted above). With onChange the user doesn't get any feedback  until the focus has changed to another control. I think onChange also has the problem that the user may not get the chance to correct the text or even know it was changed by the script. For example if the change in focus was because the user clicked on the 'run', 'ok', etc button.

A keyboard event handler stops the incorrect char from being entered into the control. The user gets feedback and doesn't have to deal with a moving insertion point.

function NumericEditKeyboardHandler (event) {
    try {
        var keyIsOK = KeyIsNumeric (event) || 
                      KeyIsDelete (event) || 
                      KeyIsLRArrow (event) ||
                      KeyIsTabEnterEscape (event);
                      
        if (! keyIsOK) {
            //    Bad input: tell ScriptUI not to accept the keydown event
            event.preventDefault();
            /*    Notify user of invalid input: make sure NOT
                to put up an alert dialog or do anything which
                requires user interaction, because that
                interferes with preventing the 'default'
                action for the keydown event */
            app.beep();
        }
    }
    catch (e) {
        ; // alert ("Ack! bug in NumericEditKeyboardHandler: " + e);
    }
}
//    key identifier functions
function KeyIsNumeric ( event ) {
    return  ( event.keyName >= '0' ) && ( event.keyName <= '9' ) && ! KeyHasModifier ( event );
}
function KeyHasModifier ( event ) {
    return event.shiftKey || event.ctrlKey || event.altKey || event.metaKey;
}
function KeyIsDelete (event) {
    //    Shift-delete is ok
    return (event.keyName == 'Backspace') && ! (event.ctrlKey);
}
function KeyIsLRArrow (event) {
    return ((event.keyName == 'Left') || (event.keyName == 'Right')) && ! (event.altKey || event.metaKey);
}
function KeyIsTabEnterEscape (event) {
    return event.keyName == 'Tab' || event.keyName == 'Enter' || event.keyName == 'Escape';
}
function createDialog( ) {
    var dlg = new Window( 'dialog', 'Example Dialog' );
    dlg.maskSt = dlg.add( 'edittext', undefined, '' );
    dlg.maskSt.preferredSize.width = 40;
    dlg.maskSt.addEventListener ('keydown', NumericEditKeyboardHandler );
   dlg.btnPnl = dlg.add( 'panel', undefined, 'Process' );
   dlg.btnPnl.orientation = "row";
   dlg.btnPnl.alignment = "right";
   dlg.btnPnl.okBtn = dlg.btnPnl.add( 'button', undefined, 'Ok', { name:'ok' });
   dlg.btnPnl.cancelBtn = dlg.btnPnl.add( 'button', undefined, 'Cancel', { name:'cancel' });
   return dlg;
};
function initializeDialog( w ) {
    w.maskSt.addEventListener ('keydown', NumericEditKeyboardHandler );
    w.maskSt.onChanging = function() {
                                    // range check if needed
                                        if( Number(this.text) < 0 || Number(this.text) > 100 ){
                                            alert('Out of range');
                                            // handle however you like
                                            this.text = '';
                                        }
                                    }
    w.btnPnl.okBtn.onClick = function ( ) { this.parent.parent.close( 1 ); };
    w.btnPnl.cancelBtn.onClick = function ( ) { this.parent.parent.close( 2 ); };
};
runDialog = function( w ) {
   return w.show( );
};
var win = createDialog();
initializeDialog( win );
runDialog( win );

Michael L Hale wrote: I think the best way to limit what is entered into an edittext control is to set up a keyboard handler. The Adobe script 'Fit Image' and 'Image Processor' has examples.

Mike I just noticed that the keyboard handler statements in CS6 Fit Image script have been commented out. So anything can be entered. You will get and error message if values ented are not numeric when you click OK. Do you know why?