URI validation in JavaScript

Question

What is a robust way (doesn't have to be regex, does it?) to validate that a URI works on Android by only using JavaScript?

That is, the check is not done in Java on the Android SDK side; it's done in a webpage using JavaScript.

EDIT: By "works on Android", I mean that Android can find an Activity that responds to an Intent using that URI.

Coset

That's exactly what I wanted to know. I thought I was just crazy. Thanks! – Coset

If you don't mind, I'd like to mark your comment as the answer. ;) – Coset

What do you mean by "validate that a URI works"? Do you mean verify that it's in a valid URI format? Or do you mean that the URI actually point to an accessible web page? The former can be done with javascript that checks for legal format. The latter requires actually downloading the web page to see if it exists and is available. – Corkscrew

@Corkscrew That's a great question. I mean that Android has an Activity to respond to an Intent with that URI. I'll update the question. Thanks! – Coset

Answer 1

Javascript is never as robust as backend but there are plenty off decent regex's around.

This is covered in another post here Trying to Validate URL Using JavaScript

The best answer I think is below

Someone mentioned the Jquery Validation plugin, seems overkill if you just want to validate the url, here is the line of regex from the plugin:

return this.optional(element) || /^(https?|ftp):\/\/(((([a-z]|\d|-|\.|_|~|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(%[\da-f]{2})|[!\$&'\(\)\*\+,;=]|:)*@)?(((\d|[1-9]\d|1\d\d|2[0-4]\d|25[0-5])\.(\d|[1-9]\d|1\d\d|2[0-4]\d|25[0-5])\.(\d|[1-9]\d|1\d\d|2[0-4]\d|25[0-5])\.(\d|[1-9]\d|1\d\d|2[0-4]\d|25[0-5]))|((([a-z]|\d|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(([a-z]|\d|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])([a-z]|\d|-|\.|_|~|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])*([a-z]|\d|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])))\.)+(([a-z]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(([a-z]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])([a-z]|\d|-|\.|_|~|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])*([a-z]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])))\.?)(:\d*)?)(\/((([a-z]|\d|-|\.|_|~|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(%[\da-f]{2})|[!\$&'\(\)\*\+,;=]|:|@)+(\/(([a-z]|\d|-|\.|_|~|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(%[\da-f]{2})|[!\$&'\(\)\*\+,;=]|:|@)*)*)?)?(\?((([a-z]|\d|-|\.|_|~|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(%[\da-f]{2})|[!\$&'\(\)\*\+,;=]|:|@)|[\uE000-\uF8FF]|\/|\?)*)?(\#((([a-z]|\d|-|\.|_|~|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(%[\da-f]{2})|[!\$&'\(\)\*\+,;=]|:|@)|\/|\?)*)?$/i.test(value);

Here is where they got it from: http://projects.scottsplayground.com/iri/

Mussel

The jQuery validation library includes support for URLs docs.jquery.com/Plugins/Validation/Methods/url. However, not all URIs are URLs. – Jon

this is invalid; gives false positive for https://df.h. – Montgomery

Answer 2

A good regex for URIs (which are a superset of URLs) surely is https://github.com/jhermsmeier/uri.regex. Unfortunately, it does not cover all types of URIs yet. However, it works in Chrome.

A more simpler version is available at http://jmrware.com/articles/2009/uri_regexp/URI_regex.html. Due to multiline, I could not include it here.

And here a step-by-step development with JUnit test cases: http://timezra.blogspot.de/2010/05/regex-to-validate-uris.html This doesn't work here "Invalid regular expression: Invalid group"

Jon

Answer 3

Simply try calling in your code:

const url = new URL(urlToCheck)

If the given urlToCheck or the resulting URL are not valid URLs,
then exception is thrown..... and then you know...

see:

https://javascript.info/url

https://developer.mozilla.org/en-US/docs/Web/API/URL/URL

Disorganization

This is not true. You could enter a non-URL function and it would return without an error. – Jiggerypokery

new URL('d:/urlToCheck.com') doesnt throw – Montgomery

URI != URL. Not all URIs are URLs. dev.to/flippedcoding/… – Petersham