UK Postcode Validation in AS3

var validPostcode:String   =  "LS12ED";
var validPostcode2:String   = "LS1 2ED";
var invalidPostcode:String =  "NOTAPOSTCODE";
 
trace(validateUkPostcode(validPostcode));//true
trace(validateUkPostcode(validPostcode2));//true
trace(validateUkPostcode(invalidPostcode));//false
 
function validateUkPostcode(str:String):Boolean {
 
	if(str.indexOf(" ")==-1){
		trace("Adding postcode space");
		var l:int = str.length;
		str=str.substr(0,l-3)+" "+str.substr(l-3,l);
	}
 
	var pattern:RegExp =  /[A-Z]{1,2}[0-9R][0-9A-Z]? [0-9][ABD-HJLNP-UW-Z]{2}/i
 
	var result:Object = pattern.exec(str);
	if(result == null) {
		return false;
	} else {
		return true;
	}
}