How to Validate an Url

Regex for website or url validation

Use the regex ^((https?|ftp|smtp):\/\/)?(www.)?[a-z0-9]+\.[a-z]+(\/[a-zA-Z0-9#]+\/?)*$

This is a basic one I build just now. A google search can give you more.

Here

^ Should start with
((https?|ftp|smtp)://)? may or maynot contain any of these protocols
(www.)? may or may not have www.
[a-z0-9]+(.[a-z]+) url and domain and also subdomain if any upto 2 levels
(/[a-zA-Z0-9#]+/?)*/? can contain path to files but not necessary. last may contain a /
$ should end there

var a=["http://www.sample.com","https://www.sample.com/","https://www.sample.com#","http://www.sample.com/xyz","http://www.sample.com/#xyz","www.sample.com","www.sample.com/xyz/#/xyz","sample.com","sample.com?name=foo","http://www.sample.com#xyz","http://www.sample.c"];var re=/^((https?|ftp|smtp):\/\/)?(www.)?[a-z0-9]+(\.[a-z]{2,}){1,3}(#?\/?[a-zA-Z0-9#]+)*\/?(\?[a-zA-Z0-9-_]+=[a-zA-Z0-9-%]+&?)?$/;a.map(x=>console.log(x+" => "+re.test(x)));

Check if a JavaScript string is a URL

A related question with an answer

Or this Regexp from Devshed:

function validURL(str) {
  var pattern = new RegExp('^(https?:\\/\\/)?'+ // protocol
    '((([a-z\\d]([a-z\\d-]*[a-z\\d])*)\\.)+[a-z]{2,}|'+ // domain name
    '((\\d{1,3}\\.){3}\\d{1,3}))'+ // OR ip (v4) address
    '(\\:\\d+)?(\\/[-a-z\\d%_.~+]*)*'+ // port and path
    '(\\?[;&a-z\\d%_.~+=-]*)?'+ // query string
    '(\\#[-a-z\\d_]*)?$','i'); // fragment locator
  return !!pattern.test(str);
}

Yup validation of website using url() very strict

Instead of using default url validator you can use your own regex. Your code changes like:

website: Yup.string()
        .matches(
            /((https?):\/\/)?(www.)?[a-z0-9]+(\.[a-z]{2,}){1,3}(#?\/?[a-zA-Z0-9#]+)*\/?(\?[a-zA-Z0-9-_]+=[a-zA-Z0-9-%]+&?)?$/,
            'Enter correct url!'
        )
        .required('Please enter website'),

You can use your own rule for regex and validate url. You can read more about it there.

Play around with it here: https://regex101.com/r/O47zyn/4

How to validate a url in Python? (Malformed or not)

django url validation regex (source):

import re
regex = re.compile(
        r'^(?:http|ftp)s?://' # http:// or https://
        r'(?:(?:[A-Z0-9](?:[A-Z0-9-]{0,61}[A-Z0-9])?\.)+(?:[A-Z]{2,6}\.?|[A-Z0-9-]{2,}\.?)|' #domain...
        r'localhost|' #localhost...
        r'\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})' # ...or ip
        r'(?::\d+)?' # optional port
        r'(?:/?|[/?]\S+)$', re.IGNORECASE)

print(re.match(regex, "http://www.example.com") is not None) # True
print(re.match(regex, "example.com") is not None)            # False

Dart / Flutter - Validating a string for URL

For some reason, the validators package is requiring a pretty recent version of flutter's testing library rather than leaving it up to the application. Maybe there's a good reason for that (i.e. they're using a new feature).

The flutter engine internally requires a particular version of the flutter_test library (which is why it's generally a bad idea to specify a version of it). So to fix this you'll have to upgrade your flutter by running flutter upgrade. If you're already at the most recent version of the channel you're in, you may have to run flutter channel dev or flutter channel master to switch to a channel (branch really) that's updated more often.

I run on the dev branch/channel for the most part and while it very occasionally has problems, it doesn't happen a lot. I'd advise against using the master branch if possible though.

URL validation in text input

Try below code, this will work for you

    function urlLocate() {
    var url = document.getElementById("url").value;
    var regexp = /^(?:(?:https?|ftp):\/\/)?(?:(?!(?:10|127)(?:\.\d{1,3}){3})(?!(?:169\.254|192\.168)(?:\.\d{1,3}){2})(?!172\.(?:1[6-9]|2\d|3[0-1])(?:\.\d{1,3}){2})(?:[1-9]\d?|1\d\d|2[01]\d|22[0-3])(?:\.(?:1?\d{1,2}|2[0-4]\d|25[0-5])){2}(?:\.(?:[1-9]\d?|1\d\d|2[0-4]\d|25[0-4]))|(?:(?:[a-z\u00a1-\uffff0-9]-*)*[a-z\u00a1-\uffff0-9]+)(?:\.(?:[a-z\u00a1-\uffff0-9]-*)*[a-z\u00a1-\uffff0-9]+)*(?:\.(?:[a-z\u00a1-\uffff]{2,})))(?::\d{2,5})?(?:\/\S*)?$/;
    if (url != "") {
        if (!regexp.test(url)) {
            alert("Please enter valid url.");
        } else {
            window.location.assign(url);
        }
    }
    else {
        alert("Please upload an image.");
    }
}