Regex for URL/String - If protocol return false

Question

Trying to create a regex in which the string should not start with http(s)://, http(s)://www. Rest of the string can be anything.

I used this regeg but its return true if we have http://

^(http://www.|https://www.|http://|https://)?[a-z0-9]+([-.]{1}[a-z0-9]+)*.[a-z]{2,5}(:[0-9]{1,5})?(/.*)?$

Another one I tried is

var re = new RegExp("(http|https|ftp)://");
var str = "http://xxxx.com";
var match = re.test(str);
console.log(match);

this one is also returning true.

Demo here

let re = /(http|https|ftp):///;
let url = 'xxxx.xxxx.xxxx'; // this is valid but test returns false
let url2 = 'https://www.xxzx.com/xxx.aspx'; // this should fail as there is https://www in url

console.log(re.test(url)); //
console.log(re.test(url2)); //

Is this possible with regex?

How do you think your regex should discard strings like you wanted? You will need to use negative lookahead in this case. — Pushpesh Kumar Rajwanshi
– Pushpesh Kumar Rajwanshi, Commented May 10, 2019 at 4:50

Pushpesh Kumar Rajwanshi · Accepted Answer · 2019-05-10 05:00:29Z

1

You need to use negative lookahead in your regex to discard strings starting with protocols like http or https or ftp. You can use this regex,

^(?!(?:ftp|https?):\/\/(www\.)?).+$

Regex Demo

JS Demo,

const arr = ['xxxx.xxxx.xxxx','ftp://www.xxzx.com/xxx.aspx','https://www.xxzx.com/xxx.aspx','http://xxxx.com','https://xxzx.com/xxx.aspx','http://www.xxxx.com']

arr.forEach(s => console.log(s + " --> " + /^(?!(?:ftp|https?):\/\/(www\.)?).+$/.test(s)))

answered May 10, 2019 at 5:00

Pushpesh Kumar Rajwanshi

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3 Comments

phantomCoder Over a year ago

Can we also make www.xxxx.com return false? Thats if it starts with www. fail. I made some changes and it worked. Is this the correct method regex101.com/r/ACBgQ9/2

Pushpesh Kumar Rajwanshi Over a year ago

Your method will do reject strings starting with www but some refinements could be done. Let me see and update.

Pushpesh Kumar Rajwanshi Over a year ago

@phantomCoder: The precise regex you need to use is this ^(?!(?:(?:ftp|https?):\/\/|www\.)).+$

howderek · Accepted Answer · 2019-05-10 05:09:44Z

1

It's probably possible to do with regexes, but unless you have to use a regex, you should use the URL class:

let HTTP_URL = 'https://www.xxzx.com/xxx.aspx'
let HTTPS_URL = 'https://www.xxzx.com/xxx.aspx'
let FTP_URL = 'ftp://www.xxzx.com/xxx.aspx'
let GOOD_PROTOCOL = 'mysql://www.xxzx.com/xxx.aspx'
let GOOD_INPUT = '129.123.12.123'

function test_url(url) {
    let bad_protocols = ['http:', 'https:', 'ftp:']
  try {
        var parsed = new URL(url)
  } catch {
    return true
  }
  return (!bad_protocols.contains(parsed.protocol))
}

test_url(HTTP_URL) //false
test_url(HTTPS_URL) //false
test_url(FTP_URL) //false
test_url(GOOD_PROTOCOL) //true
test_url(GOOD_INPUT) //true

answered May 10, 2019 at 5:09

howderek

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3 Comments

phantomCoder Over a year ago

Thanks for this, but I am looking for a regexp if possible since I am using Yup()

howderek Over a year ago

@phantomCoder you can use this with Yup using the .test() validator (medium.com/@arkadyt/…)

phantomCoder Over a year ago

Thanks for the link, I prefer a regex solution as URL class has issues with IE. +1

Rafael · Accepted Answer · 2019-05-10 04:55:18Z

0

If you're just trying to negate that regex:

function doesMatch(string) {
	return !/^http(s):\/\/(?:www)?/.test(string);
}

[
	'https://www.xxzx.com/xxx.aspx',
	'http://www.xxxx.com',
	'https://xxxx.com',
	'http://xxxx.com',
	'https://aaaa.com',
	'aaaa.com'
].forEach(s => console.log(doesMatch(s)));

answered May 10, 2019 at 4:55

Rafael

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Comments

Yamini John · Accepted Answer · 2019-05-10 05:00:06Z

0

In your example code, re.test(url) returns false , because there is no presence of http or https in that string. In url2 (ie..'https://www.xxzx.com/xxx.aspx') , there is a presence of https so it is returning true.

answered May 10, 2019 at 5:00

Yamini John

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Comments

Emma Marcier · Accepted Answer · 2019-05-10 05:18:45Z

This expression might also work, it would allow your desired input and fails all other URLs, and you can also simply add to its char list, what else might be undesired to start:

^([^http|s|ftp|www|\/\/|])*

Pass

xxxx.xxxx.xxxx

Fail

ftp://www.xxzx.com/xxx.aspx
https://www.xxzx.com/xxx.aspx
http://xxxx.com
https://xxzx.com/xxx.aspx
http://www.xxxx.com
//www.xxxx.com

You can test/modify/change it in this link.

RegEx Descriptive Graph

This graph shows how the expression would work and you can visualize other expressions in this link:

Performance Test

This JavaScript snippet shows the performance of that expression using a simple 1-million times for loop.

const repeat = 1000000;
const start = Date.now();

for (var i = repeat; i >= 0; i--) {
	const string = 'xxxx.xxxx.xxxx';
	const regex = /(^([^http|s|ftp|www|\/\/|])*)/gm;
	var match = string.replace(regex, "$1");
}

const end = Date.now() - start;
console.log("YAAAY! \"" + match + "\" is a match 💚💚💚 ");
console.log(end / 1000 + " is the runtime of " + repeat + " times benchmark test. 😳 ");

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