URL validator RegEx: code for JS and the HTML URL input pattern attribute to validate if the entry is a valid URL

url-regex-validator.md

My favorite URL RegEx

I spent way too long trying to dial this in, so I had to document my results and share them.

Check out the end result on RegExr: https://regexr.com/7fjmt

This RegEx is intended to accept nearly every valid URL, with a few exceptions; it intentionally excludes:

• IP addresses
• networks ranges, database/server addresses, ports
• any transfer protocol that isn't hypertext
• any characters that aren't standard latin a-z (A-Z) or 0-9
  • (which means unicode symbols, like "Dingbats", and other language characters are not accepted)
• http://localhost/
• data:text/plain;charset=utf-8,OHAI
• tel:+1234567890

JavaScript

const urlPattern =
  /^(https?:\/\/)((?!-)(?!.*--)[a-zA-Z\-0-9]{1,63}(?<!-)\.)+[a-zA-Z]{2,63}(\/[^\s]*)?$/;

Playground Link

HTML

<input
  type="url"
  pattern="^(https?:\/\/)((?!-)(?!.*--)[a-zA-Z\-0-9]{1,63}(?<!-)\.)+[a-zA-Z]{2,63}(\/[^\s]*)?$"
  title="Enter a valid URL"
  required
/>

JSFiddle

These valid URLs should pass:

• https://www.example.com/
• http://www.example.com/
• https://example.com/
• http://example.com/
• https://www.example.com
• http://www.example.com
• https://example.com
• http://example.com
• http://foo.com/blah_blah
• http://foo.com/blah_blah/
• http://foo.com/blah_blah_(wikipedia)
• http://foo.com/blah_blah_(wikipedia)_(again)
• http://www.example.com/wpstyle/?p=364
• https://www.example.com/foo/?bar=baz&inga=42&quux
• http://foo.com/blah_(wikipedia)#cite-1
• http://foo.com/blah_(wikipedia)_blah#cite-1
• http://foo.com/(something)?after=parens
• http://example.example.com/example/#&example=example
• http://j.mp
• http://foo.bar/?q=Test%20URL-encoded%20stuff
• http://a.b-c.de
• https://www.example.com/example
• https://example.com/example
• https://example.com/example/example/example
• https://example-example.example-example.com/example-example/
• https://example.example.com/example/example/0/#example
• https://example.com/example?example=example
• https://unpkg.com/example@1.0.0/example/example-example.html
• https://example.example.com/example/0/example-example
• https://www.example.com/index.html
• https://example.com/u/Example-Example
• https://example.com/example_example.php?example=example

These invalid URLs should fail:

• http://
• http://.
• http://..
• http://../
• http://?
• http://??
• http://??/
• http://#
• http://##
• http://##/
• http://foo.bar?q=Spaces should be encoded
• //
• //a
• ///a
• ///
• http:///a
• foo.com
• rdar://1234
• h://test
• http:// shouldfail.com
• :// should fail
• http://foo.bar/foo(bar)baz quux
• ftps://foo.bar/
• http://-error-.invalid/
• http://a.b--c.de/
• http://-a.b.co
• http://a.b-.co
• http://.www.foo.bar/
• http://www.foo.bar./
• http://.www.foo.bar./
• http://0.0.0.0
• http://10.1.1.0
• http://10.1.1.255
• http://224.1.1.1
• http://1.1.1.1.1
• http://123.123.123
• http://3628126748
• http://10.1.1.1
• http://10.1.1.254
• http://userid:password@example.com:8080
• http://userid:password@example.com:8080/
• http://userid@example.com
• http://userid@example.com/
• http://userid@example.com:8080
• http://userid@example.com:8080/
• http://userid:password@example.com
• http://userid:password@example.com/
• http://142.42.1.1/
• http://142.42.1.1:8080/
• http://-.~_!$&'()*+,;=:%40:80%2f::::::@example.com

References/Resources

I borrowed tests from Mathias Bynens' "search of the perfect URL validation regex".