isDomain() - ColdFusion UDF to perform regex to determine string is a validly formatted domain name.

isDomain.cfm

<!--- 20191230 isDomain() - Simple domain name regex
	https://gist.github.com/JamoCA/06c285c9f1e6bfcf3115dbbba0252c9a
	IDN support requires Unicode characters & punycode to be converted to its ASCII equivalent.
	Regex from https://www.regextester.com/93928 (modified to support single letter hostname like "g.co")
	Try it here: https://www.trycf.com/gist/06c285c9f1e6bfcf3115dbbba0252c9a
	Blog entry: https://dev.to/gamesover/coldfusion-isdomain-udf-1k32
--->
<cfscript>
function isDomain(inputString){
	return javacast("boolean", refindnocase("^(?!:\/\/)([a-zA-Z0-9-_]+\.)*[a-zA-Z0-9]+([a-zA-Z0-9-_])*\.[a-zA-Z]{2,11}?$", javacast("string", arguments.inputString)));
}
</cfscript>

<cfset Tests = [
	"domain.com",
	"example.domain.com",
	"example.domain-hyphen.com",
	"www.domain.com",
	"example.museum",
	"g.co",
	"dev-admin.dev-facebook-england.co.uk",
	"http://example.com",
	"subdomain.-example.com",
	"example.com/parameter",
	"example.com?anything",
	"notvalid.com.",
	".notvalid.com",
	"-notvalid.com",
	"notvalid.com-"
]>

<h2>Simple Domain Name Regex</h2>
<cfoutput>
	<ol>
		<cfloop array="#Tests#" index="thisTest">
			<li>isDomain("#thisTest#") = #isDomain(thisTest)#</li>
		</cfloop>
	<ol>
</cfoutput>