<pre class="brush:jscript;">    function validatecardfunc() {
	var validcard = false;
	var ret = stripNonNumbers( $('#eway_cc_number').val() );
	var result = $('#eway_card_type').val(); 
	if (result == "Mastercard") {
		if (ret.length == 16) 
			validcard = true;
		if ((ret.substring (0, 2) ＞= "51") &amp;&amp; (ret.substring (0, 2) ＜= "55"))
			validcard = true;
		else
			validcard = false;
	}
	if (result == "Visa") {
		if ((ret.length == 16) || (ret.length ==13))
			validcard = true;
		if (ret.substring (0, 1) != "4")
			validcard = false;
	}
	if (result == "American Express") {
		if (ret.length == 15) 
			validcard = true;
		if ((ret.substring (0, 2) != "34") &amp;&amp; (ret.substring (0, 2) != "37"))
			validcard = false;
	}
	if (result == "Discover") {
		if (ret.length == 16) 
			validcard = true;
		if (ret.substring (0, 4) != "6011")
			validcard = false;
	}
	return (validcard);
}
function stripNonNumbers (InString) { 
	OutString="";
	for (Count=0; Count ＜ InString.length; Count++) {
		TempChar=InString.substring (Count, Count+1);
		Strip = false;
		CharString="0123456789";
		for (Countx = 0; Countx ＜ CharString.length; Countx++) {
			StripThis = CharString.substring(Countx, Countx+1)
			if (TempChar == StripThis) {
				Strip = true;
				break;
			}
		}
		if (Strip)
			OutString=OutString+TempChar;
	}
	return (OutString);
}
```