Question

I need to validate a url in variable with jQuery, but can’t use validate-plugin. Is there a simple way to do this?

Answer 1

You can use the same regex that the validation plugin does (updated to latest regex on May 23rd, 2015):

function isUrlValid(url) {
    return /^(https?|s?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(url);
}

var testCases = [
    "http://www.google.com/",
    "https://www.google.com/",
    "ftp://www.google.com/",
    "http://google.com/",
    "http://google.com",
    "https://google.com",
    "http://www.google.com:80/",
    "https://www.google.com:443/",
    "http://127.0.0.1/",
    "http://127.0.0.1:9200/",
    "www.site.com",
    "x:",
    "http://",
    "javascript:alert('xss')",
    "http://w",
    "http:",
    "derp://www.google.com",
    "http://localserver"
],  div = document.getElementById("output");

for(var i=0; i < testCases.length; i++) {
    var test = testCases[i];
    div.innerHTML += (isUrlValid(test) ? "<span class='valid'>valid</span>:   " : "<span class='invalid'>invalid</span>: ") + "" + test + "\n";
}

.valid { color: green; }
.invalid { color: red; }

<pre id="output"></pre>

This handles unicode, etc so it’s a bit verbose. Source is the validation plugin itself. A few notes: it is probably what you want, but it is not strictly correct. Typically you need to choose a slightly different regex if you want to accept things like http://w and http://localserver which are valid in an intranet environment but not typically allowed in most web forms. In a way, this regex is safer because it requires a FQDN in such cases. Similarly other examples like custom protocols are rejected here, but are valid and do work for many things used today. If you’re asking users “what’s your homepage?” in a form though…you likely want to exclude these anyway.

Anyone finding this later: please feel free to test additional test cases with the snippet I included and update the answer if you feel a new common case should be mentioned. I re-wrote the answer with the latest regex and in this format to better serve the community.