Use CreditCardValidator
<?xml version="1.0" encoding="utf-8"?> <mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" layout="absolute"> <mx:VBox> <mx:ComboBox id="cardType"> <mx:dataProvider> <mx:ArrayCollection> <mx:Array> <mx:String>American Express</mx:String> <mx:String>MasterCard</mx:String> <mx:String>Visa</mx:String> </mx:Array> </mx:ArrayCollection> </mx:dataProvider> </mx:ComboBox> <mx:TextInput id="cardNumber" /> <mx:Button click="trace(validator.validate( ))" /> </mx:VBox> <mx:CreditCardValidator id="validator" cardNumberSource="{cardNumber}" cardNumberProperty="text" cardTypeSource="{cardType}" cardTypeProperty="value" /> </mx:Application>