JS URL regex, allow only urls and empty string

Question

I have the following regext:

var regex = /^(http(s)?:\/\/.)?(www\.)?[-a-zA-Z0-9@:%._\+~#=]{2,256}\.[a-z]{2,6}\b([-a-zA-Z0-9@:%_\+.~#?&//=]*)/g;

function test() {
    alert(regex.test(document.getElementById("myinput").value));
}

I want to allow url or empty string. regex solution please
How do I allow empty in this case?
https://jsfiddle.net/6kptovwc/2/
Thanks

`if (document.getElementById("myinput").value) == '') ........` — Toto, Mar 23 '20 at 13:37
`[a-z]{2,6}` is really short for TLD, see [TLD list](https://www.iana.org/domains/root/db) — Toto, Mar 23 '20 at 13:46
@Toto thanks for the inputs, noted. Anyway i was looking for a regex solution — SexyMF, Mar 23 '20 at 16:03

score 0 · Answer 1 · answered Mar 23 '20 at 13:43

0

Just add OR(||) condition

function test() {
    const elm = document.getElementById("myinput")
    alert(elm.value === '' || regex.test(elm.value));
}

answered Mar 23 '20 at 13:43

xdeepakv

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My code is just a demo. I asked for a regex solution. – SexyMF Mar 23 '20 at 15:59

score 0 · Answer 2 · answered Mar 23 '20 at 16:05

0

^$|pattern

var regex = /^$|(http(s)?:\/\/.)?(www\.)?[-a-zA-Z0-9@:%._\+~#=]{2,256}\.[a-z]{2,6}\b([-a-zA-Z0-9@:%_\+.~#?&//=]*)/g;

answered Mar 23 '20 at 16:05

SexyMF

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score 0 · Accepted Answer · answered Mar 23 '20 at 16:08

0

Add an alternation with empty string (I've simplified a bit your regex):

^((?:https?:\/\/)?(?:www\.)?[-a-zA-Z0-9@:%._\+~#=]{2,256}\.[a-z]{2,6}\b[-a-zA-Z0-9@:%_\+.~#?&\/=]*|)$

or

^((?:https?:\/\/)?(?:www\.)?[-\w@:%.+~#=]{2,256}\.[a-z]{2,6}\b[-\w@:%+.~#?&\/=]*|)$

Demo & explanation

answered Mar 23 '20 at 16:08

Toto

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What do you think about my answer? (I have found a solution) – SexyMF Mar 23 '20 at 16:51
@SexyMF: Be aware that your regex is not anchored, it matches `blah blahwww.blah.com$*!§?#~´&²` for example, and the dot in `(http(s)?:\/\/.)` matches any character between the double slash and the url, for example `https://{subdomain.domain.com` another comment is avoid capture groups when yoou don't need to capture, prefer non capture group. Nevertheless if it works for you with all your test cases, that's fine ;) – Toto Mar 23 '20 at 17:12

JS URL regex, allow only urls and empty string

3 Answers3