gistfile1.txt

function CreditCard( ccNum ){
	this.ccNum = ccNum;
	this.cardType = "INVALID"
	this.valid = false

	this.cardType = this.validStartingNums();
	if( !this.checkLength() ) return false ;
	if( !this.validate() ) return false ;

}

CreditCard.prototype.validStartingNums = function(){

	if( this.ccNum.match(/^5[1-5]/i) ){
		return 'MASTERCARD';
	}else if( this.ccNum.match(/^3[4,7]/i) ){
		return 'AMEX';
	}else if( this.ccNum.charAt(0) == '4' ){
		return 'VISA';
	}else if( this.ccNum.slice(0,4) == "6011"){
		return "DISCOVER" ;
	}else{
		return 'INVALID' ;
	}
}

CreditCard.prototype.checkLength = function(){
	switch(this.ccNum.length){
		case 15:
			if( this.cardType !== 'AMEX' ) break ;
		case 16:
			if( this.cardType == 'INVALID') break ;
			return true ;
			break ;
		default:
			return false ;
	}
	return false ;
}

CreditCard.prototype.validate = function(){
	var testNum = this.ccNum.split("").reverse().join("") ;
	var out = 0 ;
	for( var i = 0; i < testNum.length; i++){
		if( i % 2 == 0 ) continue ;
		out += Number( testNum[i] );
	}

	console.log(out % 10)
}