如何创建自定义有效 Url 正则表达式

Question

I am trying to create a regex for first time for the URL having following conditions:

1. Starts with or without the www
2. Do not starts with http:// or https://
3. Allowed special characters are: hyphen (-) and dot (.)
4. Ends with a TLD like: .com, .io, .co.in, etc.

Some of the examples for reference:

Valid:

xyz.com
xyz-px.com
www.xyz.com
abc.xyz.px.io
www.abc.xyz.px.io

Invalid:

xyz-.com
xy_pm.com
http://xyz.io
https://xyz.io
http://www.pm.xyz
xy@pzzzz.com
xyz.io$#
www.xy
xyz.io-

I have created a regex

/(^(??https|http):.\/\/(www\?.)[a-zA-Z0-9][a-zA-Z0-9-]+[a-zA-Z0-9]\,[^\s]{2,})/gi

But it is not working as desired.

Answer 1

You might use

^[^\W_]+(?:[-.][^\W_]+)*\.(?:io|com)$

The pattern matches:

• ^ Start of string
• [^\W_]+ Match 1+ word chars without an _
• (?:[-.][^\W_]+)* Optionally repeat matching . or - and 1+ word chars without _
• \. Match a literal dot
• (?:io|com) Match any of the alternatives
• $ End of string

Regex demo

Answer 2

The modified regex is

/^(?!(https|http):\/\/)(?:www\.)?[a-zA-Z0-9][a-zA-Z0-9-]+[a-zA-Z0-9](?:.[^\s\W]{2,})+$/gi

https://regex101.com/r/aNy8St/1

Answer 3

You can use

^(?!(http|https):\/\/)(?:www\.)?(?:(?:[a-zA-Z0-9])(?:[-\.][a-zA-Z0-9])?)+(?:\.[a-zA-Z0-9]+)$

DEMO - REGEXR

And the flowchart is: