HREF lang - everyone does it differently, but how is it right?

Question

Search Engine Optimization

Hello everyone, I analyzed dozens of competitors, but I still didn’t understand the answer, everyone does it differently. The hreflang attribute, how to write it correctly for a Ukrainian site in three languages, Ukrainian, Russian and English:

Option 1:

hreflang="uk"
hreflang="ru"
hreflang="en"

Option 2:

hreflang="uk-UA"
hreflang ="ru-UA"
hreflang="en-UA"

Option 3:

Option 2:

hreflang="uk_UA"
hreflang="ru_UA"
hreflang="en_UA"

Answer 1

here's an example of a project I'm working on, I did it there, and everything works

Answer 2

everything is described in the documentation
https://www.w3.org/TR/html401/struct/links.html#ad...
in the same place there are examples of lang codes
the first is correct
the second is not correct for some kind of fuck UA is prescribed for everyone, such a dialect of the same all three languages ​​cannot have, where does the Ukrainian dialect come from in English?
the third from where the underscore came from not according to the standard
in the third

Answer 3

Use the range slider . Here's a demo:
jsfiddle.net/IonDen/wsk7y08a - jump in here, add your design.

Answer 4

Yes, there are no problems if you know JS.

<input type="text" id=calc>
<span id="res"></span><p style="cursor:pointer;">OK</p>
<script>
var calc= document.getElementById('calc');
calc.onchange= function(e) {
  document.getElementById('res').textContent= eval(this.value);
}

</script>