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Comment by darepublic | Hacker News Reader

Updating pattern to support float seems viable no?

Not being a front-end dev, it does seem trivial, but using [0-9\.]* means you can have 1.2.3. You can tighten that regex up, but I imagine that either doesn't fly with mobile keyboard hinting or screen readers trying to hint what a correct value is.

This one works: `[0-9]+([\.][0-9]+)?`

> I imagine that either doesn't fly with mobile keyboard hinting or screen readers trying to hint what a correct value is

The `pattern` attribute isn't used for anything except validation as far as I know; the mobile keyboard at least is entirely driven by `inputmode` and/or `type`

Doesn't work with i18n (some countries use , instead of . as the decimal separator).

Actually the majority of the countries use the comma. Though dot wins by population as China and India use it.

https://en.m.wikipedia.org/wiki/Decimal_separator

Fwiw the pattern can be dynamic. But at that point as others have noted might be better to have a dedicated validator

It will work until you have someone from Europe get in touch early in the morning to complain your form doesn’t accept decimal commas (although they may well just roll their eyes again and mutter something about how Anglos don’t bother supporting their international users properly).

`[0-9]+([\.,][0-9]+)?` then

Getting into the weeds here though. The advantages/disadvantages of regex-based validation are beside the original point (and anyway I prefer doing validation in JS most of the time, for various reasons, but that's also out of scope)

> I prefer doing validation in JS most of the time

As you should! :) Preferably by using a parser-generator library. Validation is basically just an error mode of parsing, and parsing things with regexes is not only unreadable, but also loses a lot of valuable information about the error.

Luckily it is easy to do validation with javascript if you properly set type=number:

    if (Number.isNaN(input.valueAsNumber)) {
      // If only this message could also by localized
      input.setCustomValidity("Please type a number");
    } else {
      input.setCustomValidity("");
    }

But double luckily, we don’t even need to do this as we also get this for free, and as a bonus the message is localized.

Switzerland is in Europe.

With 1'000'000 percent certainty.

Until you come to Spain and write

8.320.320,23

…

Yep you can do that alongside this change

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